JP2018142775A - Electroacoustic transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electroacoustic conversion device capable of improving acoustic characteristics. An electroacoustic conversion device according to an embodiment of the present invention includes a housing, a piezoelectric sounding body, and a support member. The piezoelectric sounding body has a first diaphragm having a peripheral edge portion and a piezoelectric element arranged on at least one surface of the first diaphragm. The support member has a support surface that supports the peripheral edge portion, is fixed to the housing, and is made of a material having a Young's modulus of 3 GPa or more. [Selection diagram] Fig. 1

Description

  The present invention relates to an electroacoustic transducer applicable to, for example, an earphone or a headphone, a portable information terminal, or the like.

  Piezoelectric sound generating elements are widely used as simple electroacoustic conversion means, and are frequently used, for example, as acoustic devices such as earphones or headphones, and also as speakers of portable information terminals. A piezoelectric sounding element typically has a configuration in which a piezoelectric element is bonded to one or both surfaces of a diaphragm (see, for example, Patent Document 1).

  On the other hand, Patent Document 2 describes a headphone that is provided with a dynamic driver and a piezoelectric driver, and that enables reproduction with a wide bandwidth by driving these two drivers in parallel. The piezoelectric driver is provided at the center of the inner surface of the front cover that closes the front surface of the dynamic driver and functions as a diaphragm, and is configured to function as a driver for the high frequency range.

JP2013-150305A Japanese Utility Model Publication No. 62-68400

  In recent years, for example, acoustic devices such as earphones and headphones have been required to further improve sound quality. For this reason, in the piezoelectric sound generating element, it is essential to improve the characteristics of the electroacoustic conversion function. Further, it is desired to increase the sound pressure in the high sound range when combined with a dynamic speaker.

  In view of the circumstances as described above, an object of the present invention is to provide an electroacoustic transducer capable of improving acoustic characteristics.

In order to achieve the above object, an electroacoustic transducer according to one embodiment of the present invention includes a housing, a piezoelectric sounding body, and a support member.
The piezoelectric sounding body includes a first diaphragm having a peripheral portion and a piezoelectric element disposed on at least one surface of the first diaphragm.
The support member has a support surface that supports the peripheral portion, is fixed to the housing, and is made of a material having a Young's modulus of 3 GPa or more.

  According to the electroacoustic transducer, since the support member that supports the piezoelectric sounding body is made of a relatively high rigidity material having a Young's modulus of 3 GPa or more, it can stably support the vibration of the first diaphragm, As a result, it is possible to improve the sound pressure characteristics at high frequencies.

  The constituent material of the support member is not particularly limited, and for example, a metal material, a synthetic resin material, a composite material mainly composed of a synthetic resin material, or the like can be employed.

The electroacoustic transducer may further include a first adhesive material layer. The first adhesive material layer is disposed between the support surface and the peripheral portion, and elastically supports the peripheral portion with respect to the support surface.
Thereby, the vibration of resonance of the first diaphragm is suppressed, and a stable resonance operation of the first diaphragm is ensured.

The housing includes a first housing portion that supports the support member, and a second housing portion that covers the piezoelectric sounding body and is joined to the first housing portion. The support member may further include a first annular piece that surrounds the peripheral edge. In this case, the electroacoustic transducer further includes a second adhesive material layer disposed between the peripheral edge portion and the second housing portion, and the second adhesive material layer includes the second adhesive material layer. The first annular piece portion is elastically supported with respect to the two housing portions.
Accordingly, the support member can be elastically sandwiched between the first housing portion and the second housing portion, so that the piezoelectric sounding body can be stably supported by the support member.

The piezoelectric sounding body may further include a passage portion that penetrates the first diaphragm in the thickness direction.
In this case, the electroacoustic transducer may further include an electromagnetic sounding body including a second diaphragm. The housing communicates with the first space portion where the electromagnetic sounding body is disposed, the first space portion via the passage portion, and includes the piezoelectric sounding body and the electromagnetic sounding body. And a second space portion having a sound guide path for guiding the generated sound wave to the outside.
Thereby, it is possible to improve the sound pressure characteristics from the low sound range to the high sound range.

The electromagnetic sounding body further includes a main body portion that supports the second diaphragm so as to vibrate, and the support member is provided on a surface opposite to the support surface, and an outer peripheral edge portion of the main body portion. You may further have the 2nd annular piece part to engage.
As a result, the relative positioning accuracy between the electromagnetic sounding body and the piezoelectric sounding body is improved, and the rigidity of the support member can be further increased.

  As described above, according to the present invention, the acoustic characteristics can be improved.

It is a schematic sectional side view which shows the structure of the electroacoustic transducer concerning the 1st Embodiment of this invention. It is sectional drawing of the principal part which shows one structural example of the electromagnetic sounding body in the said electroacoustic transducer. It is a schematic plan view of the piezoelectric sounding body in the electroacoustic transducer. It is a schematic sectional drawing which shows the internal structure of the piezoelectric element in the said piezoelectric type sounding body. It is a schematic plan view of the support member in the electroacoustic transducer. It is a disassembled sectional side view of the sound generation unit containing the said supporting member. It is one experimental result which shows the sound pressure characteristic of the piezoelectric sounding body measured by changing the material of the said supporting member. It is one experimental result which shows the relationship between the Young's modulus of the said support member, and the sound pressure level of a piezoelectric type sounding body. It is a sectional side view which shows roughly the structure of the electroacoustic transducer which concerns on the 2nd Embodiment of this invention. It is a schematic sectional side view of the support member in the said electroacoustic transducer.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a schematic sectional side view showing a configuration of an earphone 100 as an electroacoustic transducer according to an embodiment of the present invention.
In the figure, an X axis, a Y axis, and a Z axis indicate triaxial directions orthogonal to each other.

[Overall configuration of earphone]
The earphone 100 includes an earphone main body 10 and an earpiece 20. The earpiece 20 is attached to the sound guide path 41 of the earphone body 10 and is configured to be attachable to the user's ear.

  The earphone main body 10 includes a sound generation unit 30 and a housing 40 that houses the sound generation unit 30. The sounding unit 30 includes an electromagnetic sounding body 31 and a piezoelectric sounding body 32.

[Case]
The housing 40 has an internal space that accommodates the sound generation unit 30 and has a two-part structure that can be separated in the Z-axis direction. A sound guide path 41 that guides sound waves generated by the sound generation unit 30 to the outside is provided on one end surface (upper end surface in the drawing) 410 of the housing 40.

  The housing 40 is configured by a combination of a first housing portion 401 and a second housing portion 402. The first housing unit 401 has a housing space for housing the sound generation unit 30 therein. The second housing portion 402 has a sound guide path 41 and is combined with the first housing portion 401 in the Z-axis direction to cover the piezoelectric sounding body 32.

  The internal space of the housing 40 is partitioned by the piezoelectric sounding body 32 into a first space portion S1 and a second space portion S2. An electromagnetic sounding body 31 is disposed in the first space S1. The second space portion S <b> 2 is a space portion that communicates with the sound guide path 41, and is formed between the piezoelectric sounding body 32 and the bottom portion 410 of the housing 40. The first space portion S1 and the second space portion S2 communicate with each other via the passage portion 330 of the piezoelectric sounding body 32.

[Electromagnetic sound generator]
The electromagnetic sounding body 31 includes a dynamic speaker unit that functions as a woofer that reproduces a low frequency range. In this embodiment, for example, a dynamic speaker that mainly generates sound waves of 7 kHz or less, a mechanism unit 311 including a vibrating body such as a voice coil motor (electromagnetic coil), and a pedestal unit 312 that supports the mechanism unit 311 so as to vibrate. And have.

  The structure of the mechanism part 311 of the electromagnetic sounding body 31 is not particularly limited. FIG. 2 is a cross-sectional view of a main part showing one configuration example of the mechanism unit 311. The mechanism 311 includes a diaphragm E1 (second diaphragm) supported by the pedestal 312 so as to vibrate, a permanent magnet E2, a voice coil E3, and a yoke E4 that supports the permanent magnet E2. The diaphragm E1 is supported by the pedestal portion 312 by sandwiching the peripheral edge portion between the bottom portion of the pedestal portion 312 and the annular fixture 310 assembled integrally therewith.

  The voice coil E3 is formed by winding a conductive wire around a bobbin serving as a winding core, and is joined to the central portion of the diaphragm E1. The voice coil E3 is disposed perpendicular to the direction of the magnetic flux of the permanent magnet E2. When an alternating current (voice signal) is passed through the voice coil E3, an electromagnetic force acts on the voice coil E3, so that the voice coil E3 vibrates in the Z-axis direction in the drawing according to the signal waveform. This vibration is transmitted to the diaphragm E1 connected to the voice coil E3, and the sound in the low frequency range is generated by vibrating the air in the first space S1 (FIG. 1).

  The electromagnetic sounding body 31 is fixed inside the housing 40 by an appropriate method. A circuit board 33 constituting an electric circuit of the sounding unit 30 is fixed on the electromagnetic sounding body 31. The circuit board 33 is electrically connected to the cable 50 introduced via the lead portion 42 of the housing 40, and sends an electrical signal to the electromagnetic sounding body 31 and the piezoelectric sounding body 32 via a wiring member (not shown). Output.

[Piezoelectric sounding body]
The piezoelectric sounding body 32 constitutes a speaker unit that functions as a tweeter that reproduces a high frequency range. In this embodiment, for example, the oscillation frequency is set so as to mainly generate sound waves of 7 kHz or higher. The piezoelectric sounding body 32 includes a diaphragm 321 (first diaphragm) and a piezoelectric element 322.

  The vibration plate 321 is made of a conductive material such as metal (for example, 42 alloy) or an insulating material such as resin (for example, liquid crystal polymer), and its planar shape is formed in a substantially circular shape. The “substantially circular” means not only a circular shape but also a substantially circular shape 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 40, the frequency band of the reproduced sound wave, and the like. In this embodiment, a diaphragm having a diameter of about 8 to 12 mm and a thickness of about 0.2 mm is used.

  The diaphragm 321 may have a notch formed in a concave shape or a slit shape that is recessed from the outer periphery toward the inner periphery as necessary. Note that the planar shape of the diaphragm 321 is substantially circular if the rough shape is circular, even if it is not strictly circular due to the formation of the notch.

The diaphragm 321 has a first main surface 32 a that faces the sound guide path 41 and a second main surface 32 b that faces the electromagnetic sounding body 31. In the present embodiment, the piezoelectric sounding body 32 has a unimorph structure in which the piezoelectric element 322 is bonded only to the first main surface 32 a of the diaphragm 321.
The piezoelectric element 322 may be bonded to the second main surface 32b of the diaphragm 321 without being limited thereto. The piezoelectric sounding body 32 may have a bimorph structure in which piezoelectric elements are joined to both main surfaces 32 a and 32 b of the diaphragm 321.

  FIG. 3 is a plan view of the piezoelectric sounding body 32.

  As shown in FIG. 3, the planar shape of the piezoelectric element 322 is rectangular, and the central axis of the piezoelectric element 322 is typically arranged coaxially with the central axis C <b> 1 of the diaphragm 321. The center axis of the piezoelectric element 322 may be displaced by a predetermined amount, for example, in the X-axis direction from the center axis C1 of the diaphragm 321. That is, the piezoelectric element 322 may be disposed at a position eccentric with respect to the diaphragm 321. As a result, the vibration center of the diaphragm 321 is shifted to a position different from the center axis C 1, so that the vibration mode of the piezoelectric sounding body 32 is asymmetric with respect to the center axis C 1 of the diaphragm 321. Therefore, for example, by bringing the vibration center of the diaphragm 321 closer to the sound guide path 41, the sound pressure characteristics in the high sound range can be further improved.

  The diaphragm 321 has a plurality of passage portions 330 in its plane. These passage portions 330 constitute passage portions that penetrate the diaphragm 321 in the thickness direction, and include a first opening 331 and a second opening 332. The passage portion 330 allows the first space portion S1 and the second space portion S2 to communicate with each other inside the housing 40.

  The first opening 331 is configured by a plurality of circular holes provided in a region between the peripheral edge 321 c of the diaphragm 321 and the piezoelectric element 322. These first openings 331 are respectively provided at positions symmetrical with respect to the center axis C1 on the center line CL (a line parallel to the Y-axis direction passing through the center of the diaphragm 321). Each of the first openings 331 is formed by a round hole having the same diameter (for example, a diameter of about 1 mm), but is not limited thereto.

  The second opening 332 is provided between the peripheral edge 321c and the piezoelectric element 322, and is formed in a rectangular shape having a long side in the Y-axis direction. The second opening 332 is formed along the peripheral edge of the piezoelectric element 322, and a part of the second opening 332 is partially covered by the peripheral edge of the piezoelectric element 322. The second opening 332 has a function of preventing a short circuit between two external electrodes of the piezoelectric element 322 as described later, in addition to a function as a passage penetrating the front and back of the diaphragm 321.

  FIG. 4 is a schematic cross-sectional view showing the internal structure of the piezoelectric element 322.

  The piezoelectric element 322 includes an element body 328 and a first external electrode 326a and a second external electrode 326b that face each other in the XY axis direction. In addition, the piezoelectric element 322 has a first main surface 322a and a second main surface 322b that are perpendicular to the Z-axis and face each other. The second main surface 322 b of the piezoelectric element 322 is configured as a mounting surface that faces the first main surface 32 a of the diaphragm 321.

  The element body 328 has a structure in which a ceramic sheet 323 and internal electrode layers 324a and 324b are stacked in the Z-axis direction. That is, the internal electrode layers 324a and 324b are alternately stacked with the ceramic sheet 323 interposed therebetween. The ceramic sheet 323 is made of, for example, a piezoelectric material such as lead zirconate titanate (PZT) or an alkali metal-containing niobium oxide. The internal electrode layers 324a and 324b are formed of conductive materials such as various metal materials.

  The first internal electrode layer 324 a of the element body 328 is connected to the first external electrode 326 a and is insulated from the second external electrode 326 b by the margin portion of the ceramic sheet 323. The second internal electrode layer 324b of the element body 328 is connected to the second external electrode 326b and insulated from the first external electrode 326a by the margin portion of the ceramic sheet 323.

  In FIG. 4, the uppermost layer of the first internal electrode layer 324a constitutes a first extraction electrode layer 325a that partially covers the surface of the element body 328 (the upper surface in FIG. 4), and the second internal electrode layer The lowermost layer of 324b constitutes a second extraction electrode layer 325b that partially covers the back surface (lower surface in FIG. 4) of the element body 328. The first extraction electrode layer 325a has a terminal portion 327a of one pole electrically connected to the circuit board 33 (FIG. 1), and the second extraction electrode layer 325b is interposed via an appropriate bonding material. It is electrically and mechanically connected to the first main surface 32a of the diaphragm 321. When the vibration plate 321 is made of a conductive material, a conductive bonding material such as a conductive adhesive or solder may be used as the bonding material. In this case, the terminal portion of the other electrode is connected to the vibration plate. 321 can be provided.

  The first and second external electrodes 326a and 326b are formed of conductive materials such as various metal materials at substantially central portions of both end surfaces of the element body 328 in the X-axis direction. The first external electrode 326a is electrically connected to the first internal electrode layer 324a and the first extraction electrode layer 325a, and the second external electrode 326b is connected to the second internal electrode layer 324b and the second extraction electrode It is electrically connected to the electrode layer 325b.

  With this configuration, when an AC voltage is applied between the external electrodes 326a and 326b, the ceramic sheets 323 between the internal electrode layers 324a and 324b expand and contract at a predetermined frequency. Thereby, the piezoelectric element 322 can generate vibration applied to the diaphragm 321.

  Here, as shown in FIG. 4, the first and second external electrodes 326 a and 326 b protrude from the both end surfaces of the element body 328, respectively. At this time, the first and second external electrodes 326a and 326b may be formed with raised portions 329a and 329b protruding toward the first main surface 32a of the diaphragm 321. Therefore, the opening 333 described above is formed in a size that can accommodate the raised portions 329a and 329b. This prevents an electrical short circuit between the external electrodes 326a and 326b due to contact between the raised portions 329a and 329b and the diaphragm 321.

[Support member]
Next, details of the support member 50 will be described.

  The earphone 100 includes a support member 50 that supports the piezoelectric sounding body 32 so as to vibrate inside the housing 40. FIG. 5 is a schematic plan view of the support member 50, and FIG. 6 is an exploded side sectional view of the sound generation unit 30 including the support member 50.

  The support member 50 is configured by a ring-shaped (annular) block body as shown in FIG. The support member 50 includes a support surface 51 that supports the peripheral portion 321c of the diaphragm 321 of the piezoelectric sounding body 32, an outer peripheral surface 52 that faces the inner wall surface of the housing 40, and an inner periphery that faces the first space S1. It has the surface 53, the front end surface 54 joined to the housing | casing 40 (2nd housing | casing part 402), and the bottom face 55 joined to the peripheral part of the electromagnetic sounding body 31. As shown in FIG.

  The support surface 51 is joined to the peripheral portion 321c of the vibration plate 321 via an annular adhesive material layer 61 (first adhesive material layer). Thereby, since the diaphragm 321 is elastically supported with respect to the support member 50, the vibration of the vibration of the diaphragm 321 is suppressed, and the stable resonance operation of the diaphragm 321 is ensured.

  Further, the front end surface 54 is joined to the inner peripheral edge of the second casing portion 402 via an annular pressure-sensitive adhesive layer 62 (second pressure-sensitive adhesive layer). The bottom surface 55 is joined to the electromagnetic sound producing body 31 via an annular adhesive material layer 63 (third adhesive material layer). Accordingly, since the support member 50 can be elastically sandwiched between the first housing portion 401 and the second housing portion 402, the piezoelectric sounding body 32 is stably supported by the support member 50. be able to.

  The pressure-sensitive adhesive layers 61 to 63 are made of a material having moderate elasticity, and are typically made of double-sided pressure-sensitive adhesive tapes each cut with a predetermined diameter. In addition to this, the pressure-sensitive adhesive layers 61 to 63 may be composed of a cured viscoelastic resin, a pressure-adhesive viscoelastic film, or the like. Further, the pressure-sensitive adhesive layers 61 to 63 are formed of an annular body, so that the airtightness between the electromagnetic sounding body 31 and the support member 50, the airtightness between the support member 50 and the diaphragm 321, and The airtightness between the support member 50 and the housing 40 is enhanced, and sound waves generated in the first and second space portions S1 and S2 can be efficiently guided to the sound guide path 41.

  Here, the support member 50 is made of a material having a Young's modulus (longitudinal elastic modulus) of 3 GPa or more. Since the support member 50 made of such a material can ensure a relatively high rigidity, the piezoelectric sounding body 31 (the diaphragm 321) that vibrates in a relatively high frequency band of 7 kHz or more can be stably supported. can do.

  The upper limit of the Young's modulus of the material constituting the support member 50 is not particularly limited. However, for example, a material alone of 5 GPa or more is almost limited to inorganic materials such as metals and ceramics. Can be set as appropriate, for example, 500 GPa or less. On the other hand, the support member 50 made of a synthetic resin material is advantageous in terms of weight reduction and productivity.

Examples of the material having a Young's modulus of 3 GPa or more include metal materials, ceramics, synthetic resin materials, and composite materials mainly composed of synthetic resin materials. As the metal material, in addition to ferrous materials such as rolled steel, stainless steel, and cast iron, non-ferrous materials such as aluminum and brass can be used without particular limitation. As the ceramic, an appropriate material such as SiC or Al ₂ O ₃ is applicable.

  Examples of the synthetic resin material include polyphenylene sulfide (PPS), polymethyl methacrylate (PMMA), polyacetal (POM), hard vinyl chloride, methyl methacrylate / styrene copolymer (MS), and the like. Even if it is a resin material such as polycarbonate (PC) or styrene / butadiene / acrylonitrile copolymer (ABS) that does not have a Young's modulus of 3 GPa or more, it can be made of fibers and inorganic particles such as glass fibers. It is possible to employ a composite material (reinforced plastic) having a Young's modulus (longitudinal elastic modulus) of 3 GPa or more to which a filler (filler) made of fine particles such as the above is added.

  The support member 50 may not be a simple plate material but may be formed in a three-dimensional shape having a different thickness depending on the region. Thereby, the cross-sectional secondary moment can be increased, and even if the material has the same Young's modulus, the rigidity (bending rigidity) can be further increased.

  For example, the support member 50 in the present embodiment is provided with an annular piece 56 (first annular piece) that protrudes upward along the outer peripheral edge of the support surface 51 and surrounds the peripheral edge 321 c of the diaphragm 321. (Refer to FIG. 6), and the tip surface 54 described above is formed on the top thereof. Thereby, since the outer peripheral side of the support member 50 is thicker than the inner peripheral side, the rigidity against twisting and bending is enhanced.

[Earphone operation]
Subsequently, a typical operation of the earphone 100 of the present embodiment configured as described above will be described.

  In the earphone 100 of the present embodiment, a reproduction signal is input to the circuit board 33 of the sound generation unit 30 via the cable 50. The reproduction signal is input to the electromagnetic sounding body 31 and the piezoelectric sounding body 32 via the circuit board 33. Thereby, the electromagnetic sounding body 31 is driven, and a sound wave in a low frequency range of 7 kHz or less is mainly generated. On the other hand, in the piezoelectric sounding body 32, the diaphragm 321 vibrates due to the expansion / contraction operation of the piezoelectric element 322, and mainly high-frequency sound waves of 7 kHz or higher are generated. The generated sound wave of each band is transmitted to the user's ear via the sound guide path 41. As described above, the earphone 100 functions as a hybrid speaker having a low-frequency sounding body and a high-frequency sounding body.

  On the other hand, the 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 S2 and the second space portion via the passage portion 330. It is formed by a synthesized wave with a sound wave component propagating to S2. Therefore, by optimizing the size and number of the passage portions 330, the low frequency sound wave output from the piezoelectric sounding body 32 has a frequency characteristic such that a sound pressure peak can be obtained in a predetermined low frequency band, for example. Adjustment or tuning is possible.

  In the present embodiment, since the support member 50 is made of a material having a Young's modulus of 3 GPa or higher, for example, as shown in FIG. 7, the sound pressure level is significantly increased in a high frequency band of 9 kHz or higher, thereby realizing a clear sound quality. can do.

  FIG. 7 is an experimental result showing the sound pressure characteristics of the piezoelectric sounding body 32 measured with different materials for the support member 50. In the figure, the vertical axis indicates the sound pressure level, and the horizontal axis indicates the frequency. As a constituent material of the supporting member, SUS (solid line) with Young's modulus of 197 GPa, PPS (single-dot chain line) with 3.7 GPa, and 2.3 GPa PC (dashed line) was used.

  As shown in the figure, the sound pressure level when using a support member made of SUS and PPS is improved from around 9 kHz to around 20 kHz than the sound pressure level when using a support member made of PC. This is because when the Young's modulus is less than 3 GPa, the piezoelectric sounding body that vibrates at a frequency of 9 kHz or more cannot be stably supported, and as a result, the vibration of the diaphragm 321 is attenuated by the vibration of the support member itself. This is probably because of this. On the other hand, by using a highly rigid support member having a Young's modulus of 3 GPa or more, it becomes possible to more stably support the diaphragm 321 that vibrates at a high frequency, thereby improving the sound pressure level in the high frequency band. Can be achieved.

FIG. 8 shows one experimental result showing the relationship between the Young's modulus of the support member 50 and the average sound pressure level (SPL) of the piezoelectric sounding body 32 at 8 kHz to 20 kHz.
Here, five types of materials having different Young's moduli were used to constitute samples A to E of the support member, and the sound pressure levels of samples B to E were represented by differences from those of sample A. The constituent materials (Young's modulus) of each sample are as follows.

Sample A: PC (2.3 GPa)
Sample B: Reinforced PC (3.1 GPa)
Sample C: PPS (3.7 GPa)
Sample D: SUS301 (197 GPa)
Sample E: SiC (500 GPa)
Samples A, C, and D correspond to the materials indicated by the broken line, the alternate long and short dash line, and the solid line in FIG.

  As shown in FIG. 8, in Samples B to E having a Young's modulus of 3 GPa or more, an improvement in sound pressure level of +5 dB or more is recognized as compared with Sample A having a Young's modulus of less than 3 GPa. As described above, by configuring the support member 50 with a material having a Young's modulus of 3 GPa or more, the sound pressure in the high frequency band from 8 kHz to 20 kHz can be efficiently increased, thereby improving the acoustic characteristics in the high sound range. It becomes possible to plan.

<Second Embodiment>
FIG. 9 is a side sectional view schematically showing the configuration of the earphone 200 according to the second embodiment of the present invention, and FIG. 10 is a schematic side sectional view of the support member 70. In FIG. 9, the housing 40 is not shown for easy understanding.
Hereinafter, the configuration different from the first embodiment will be mainly described, and the same configuration as the first embodiment will be denoted by the same reference numeral, and the description thereof will be omitted or simplified.

  The earphone 200 of the present embodiment is different from the first embodiment in the configuration of the support member 70 that supports the piezoelectric sounding body 32. That is, the support member 70 is common to the first embodiment in that it includes a support surface 51, an outer peripheral surface 52, an inner peripheral surface 53, a tip surface 54, a bottom surface 55, and a first annular piece portion 56. However, the second embodiment differs from the first embodiment in that it further includes a second annular piece 57 projecting downward from the outer peripheral edge of the bottom surface 55.

  In the present embodiment, the support member 70 is made of a material having a Young's modulus of 3 GPa or more, like the support member 50 of the first embodiment. Further, in the present embodiment, since the support member 70 is further provided with the second annular piece portion 57 at the outer peripheral edge portion of the bottom surface 55, higher rigidity than the support member 50 can be obtained. Therefore, the piezoelectric sounding body 32 that vibrates in a high frequency region can be supported more stably.

  As shown in FIG. 9, the second annular piece portion 57 may be configured to engage with the outer peripheral edge portion of the electromagnetic sounding body 31 (main body portion 312). Thereby, the relative positioning accuracy between the electromagnetic sounding body 31 and the piezoelectric sounding body 32 and the assembly workability can be improved.

  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.

  For example, in the above embodiment, the electroacoustic transducer having both the electromagnetic sounding body 31 and the piezoelectric sounding body 32 has been described as an example. However, the electroacoustic transducer having only the piezoelectric sounding body is described as an example. The present invention is also applicable.

  In the above embodiment, the earphone has been described as an example of the electroacoustic conversion device. However, the present invention is not limited to this, and the present invention can also be applied to headphones, stationary speakers, speakers built in portable information terminals, and the like. is there.

31 ... Electromagnetic sound generator 32 ... Piezoelectric sound generator 40 ... Housing 50, 70 ... Support member 51 ... Support surface 56, 57 ... Ring piece 61-63 ... Adhesive material layer 100, 200 ... Earphone 321 ... Diaphragm 322 ... Piezoelectric element 330 ... Passage part 401 ... First casing part 402 ... Second casing part

Claims (8)

A housing,
A piezoelectric sounding body having a first diaphragm having a peripheral edge and a piezoelectric element disposed on at least one surface of the first diaphragm; a support surface for supporting the peripheral edge; An electroacoustic transducer comprising: a support member fixed to a body and made of a material having a Young's modulus of 3 GPa or more. The electroacoustic transducer according to claim 1,
The said support member is an electroacoustic transducer comprised with the cyclic | annular block body comprised with the metal material. The electroacoustic transducer according to claim 1,
The said support member is an electroacoustic transducer comprised by the cyclic | annular block body comprised with the composite material which has a synthetic resin material or a synthetic resin material as a main body. The electroacoustic transducer according to any one of claims 1 to 3,
An electroacoustic transducer, further comprising a first adhesive layer disposed between the support surface and the peripheral portion and elastically supporting the peripheral portion with respect to the support surface. The electroacoustic transducer according to claim 4,
The housing includes a first housing portion that supports the support member, and a second housing portion that covers the piezoelectric sounding body and is joined to the first housing portion.
The support member further includes a first annular piece that surrounds the periphery.
The electroacoustic transducer further includes a second adhesive material layer disposed between the first annular piece portion and the second housing portion, and the second adhesive material layer includes: An electroacoustic transducer that elastically supports the first annular piece with respect to a second casing. The electroacoustic transducer according to any one of claims 1 to 5,
The piezoelectric sounding device further includes a passage portion that penetrates the first diaphragm in a thickness direction. The electroacoustic transducer according to claim 6,
An electromagnetic sounding body including a second diaphragm;
The housing is
A first space in which the electromagnetic sounding body is disposed;
A second space portion having a sound guide path that communicates with the first space portion via the passage portion and guides sound waves generated by the piezoelectric sounding body and the electromagnetic sounding body to the outside. An electroacoustic transducer. The electroacoustic transducer according to claim 7,
The electromagnetic sounding body further includes a main body that supports the second diaphragm so as to vibrate,
The electroacoustic transducer according to claim 1, wherein the support member further includes a second annular piece that is provided on a surface opposite to the support surface and engages with an outer peripheral edge of the main body.

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