JP5759642B1 - Electroacoustic transducer - Google Patents

Abstract

A piezoelectric sounding body capable of ensuring good assembly and an electroacoustic transducer provided with the piezoelectric sounding body are provided. An electroacoustic transducer (earphone 100) according to an embodiment of the present invention includes a diaphragm 321, a piezoelectric element 322, and a plurality of wiring members C3. The piezoelectric element 322 has a structure in which a plurality of piezoelectric layers and a plurality of electrode layers are alternately stacked, and is joined to one main surface 32 b of the diaphragm 321. The plurality of wiring members C3 are electrically connected to the plurality of electrode layers, and are drawn from the piezoelectric element 322 to the one main surface 32b side of the diaphragm 321. [Selection] Figure 1

Description

  The present invention relates to a piezoelectric sounding body applicable to, for example, an earphone or a headphone, a portable information terminal, and the like, and an electroacoustic transducer having the same.

  Piezoelectric sounding bodies 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. The piezoelectric sounding element typically has a configuration in which piezoelectric elements are bonded to both surfaces of a diaphragm (see, for example, Patent Document 1).

JP2013-150305A

  In recent years, there has been a demand for improved assembly of electroacoustic transducers having a piezoelectric sounding body. For example, when piezoelectric elements are bonded to both surfaces of the diaphragm, it is necessary to pull out the wiring from each surface of the diaphragm. Therefore, it is not possible to pull out the wiring connected to one of the surfaces to the other surface in the housing. This is not easy, and it may be a factor that hinders assembling properties, and stable vibration of the diaphragm may not be ensured.

  In view of the circumstances as described above, an object of the present invention is to provide a piezoelectric sounding body capable of ensuring good assemblability and an electroacoustic transducer having the piezoelectric sounding body.

In order to achieve the above object, an electroacoustic transducer according to one embodiment of the present invention includes a diaphragm, a piezoelectric element, and a plurality of wiring members.
The piezoelectric element has a structure in which a plurality of piezoelectric layers and a plurality of electrode layers are alternately stacked, and is bonded to one main surface of the diaphragm.
The plurality of wiring members are electrically connected to the plurality of electrode layers, and are drawn from the piezoelectric element to one main surface side of the diaphragm.

  The piezoelectric sounding body is configured such that all of the plurality of wiring members are drawn out to one main surface side of the diaphragm, so that the piezoelectric element is compared with the case where the wiring is drawn out from the other main surface side of the diaphragm. It is possible to improve not only the workability of connecting the wiring member to the housing but also the ease of assembly to the housing.

An electroacoustic transducer according to an embodiment of the present invention includes a diaphragm, a piezoelectric element, a plurality of wiring members, and a sounding body.
The piezoelectric element has a structure in which a plurality of piezoelectric layers and a plurality of electrode layers are alternately stacked, and is bonded to one main surface of the diaphragm.
The plurality of wiring members are electrically connected to the plurality of electrode layers, and are drawn from the piezoelectric element to one main surface side of the diaphragm.
The sounding body has a first surface facing the one main surface.

  In the electroacoustic transducer, since a plurality of wiring members electrically connected to the piezoelectric element are drawn out to one main surface side of the diaphragm, each wiring member can be easily connected to the sounding body. Thereby, the assemblability can be improved.

  As described above, according to the present invention, it is possible to ensure good assembly.

It is a schematic sectional side view which shows the electroacoustic transducer which concerns on one Embodiment of this 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. It is a schematic plan view of the electromagnetic 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 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 plan view which shows one structural example of the piezoelectric sounding body which concerns on other embodiment of this invention. FIG. 13 is a schematic plan view illustrating another configuration example of the piezoelectric sounding body illustrated in FIG. 12. It is a schematic sectional side view which shows the electroacoustic transducer which concerns on other embodiment of this invention. FIG. 15 is a schematic plan view showing a configuration example of a piezoelectric sounding body in the electroacoustic transducer of FIG. 14. 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 further another structural example of the said piezoelectric 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 electroacoustic transducer which concerns on this invention.

  Hereinafter, embodiments according to 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 path 11 of the earphone body 10 and is configured to be attachable to the user's ear.

The earphone 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. The housing 40 includes a housing 41 and a cover 42.

[Case]
The casing 41 has a bottomed cylindrical shape, and is typically formed of a plastic injection molded body. The casing 41 has an internal space for accommodating the sound generation unit 30, and a sound path 11 that communicates with the internal space is provided at the bottom portion 410.

  The housing 41 includes a support portion 411 that supports the peripheral portion of the piezoelectric sounding body 32, and a side wall portion 412 that surrounds the sounding unit 30. The support part 411 and the side wall part 412 are both formed in an annular shape, and the support part 411 is provided so as to protrude inward from the vicinity of the bottom part of the side wall part 412. The support part 411 is formed in a plane parallel to the XY plane, and supports a peripheral part of a piezoelectric sounding body 32 described later directly or indirectly through another member. In addition, the support part 411 may be comprised with the some columnar body arrange | positioned cyclically | annularly along the internal peripheral surface of the side wall part 412. FIG.

[Electromagnetic sound generator]
The electromagnetic sounding body 31 includes a 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 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 peripheral surface portion 31 e that fits into the side wall portion 412.

  FIG. 2 is a schematic sectional side view of the sound generation unit 30 before being assembled to the housing 41, and FIG. 3 is a schematic plan view of the sound generation unit 30.

  The electromagnetic sounding body 31 has a disk shape having a first surface 31a facing the piezoelectric sounding body 32 and a second surface 31b opposite to the first surface 31a. A leg portion 312a is provided at the peripheral portion of the first surface 31a so as to face the peripheral portion of the piezoelectric sounding body 32 so as to be in contact therewith. The leg portion 312a is formed in an annular shape, but is not limited thereto, and may be composed of a plurality of pillars.

  The second surface 31b is formed on the surface of a disk-like raised portion 31c provided at the center of the upper surface of the pedestal portion 312. A circuit board 33 constituting an electric circuit of the sound generation unit 30 is fixed to the second surface 31b. As shown in FIG. 3, a plurality of terminal portions 331, 332, and 333 connected to various wiring members are provided on the surface of the circuit board 33. The circuit board 33 is typically composed of a wiring board, but may be a board provided with at least a terminal portion to which each wiring member is connected. In addition, the circuit board 33 is not limited to the example provided on the second surface 31b, and may be provided on another part such as an inner wall portion of the cover 42, for example.

  Each terminal portion 331 to 333 is provided in pairs. The terminal member 331 is connected to a wiring member C1 for inputting a reproduction signal transmitted from a reproduction device (not shown). The terminal portion 332 is electrically connected to the input terminal 313 of the electromagnetic sounding body 31 via the wiring member C2. The terminal portion 333 is electrically connected to the input terminals 324 and 325 of the piezoelectric sounding body 32 via 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 therebetween.

[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 and a piezoelectric element 322.

  The diaphragm 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 circle. The outer diameter and thickness of the diaphragm 321 are not particularly limited, and are appropriately set according to the size of the casing 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 sounding body 31. In this embodiment, a diaphragm having a diameter of about 12 mm and a thickness of about 0.2 mm is used.

  As shown in FIG. 3, the diaphragm 321 has a peripheral edge 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 edge portion 321 c of the diaphragm 321. The annular member 34 has a support surface 341 that supports the legs 312 a of the electromagnetic sounding body 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.

  The material which comprises the annular member 34 is not specifically limited, For example, it comprises with elastic materials, such as a metal material, a synthetic resin material, and rubber | gum. When the annular member 34 is made of an elastic material such as rubber, the vibration of the vibration of the diaphragm 321 is suppressed, and thereby a stable resonance operation of the diaphragm 321 can be ensured.

  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 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 second main surface 32 b of the diaphragm 321.

  FIG. 4 is a schematic perspective view showing a configuration example of the piezoelectric element 322, and FIG. 5 is a schematic cross-sectional view thereof. 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.

  The planar shape of the piezoelectric element 322 is formed in a polygonal shape and is a rectangle (rectangular shape) in the present embodiment. However, other quadrangles such as a square, a parallelogram, and a trapezoid, or a polygon other than a rectangle, It may be circular, elliptical, oval, etc. The thickness of the piezoelectric element 322 is not particularly limited, and is about 50 μm, for example.

  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 is formed by laminating a plurality of ceramic sheets Ld having piezoelectric properties such as lead zirconate titanate (PZT) and alkali metal-containing niobium oxide with the electrode layer Le interposed therebetween. It is produced by firing at a predetermined temperature. One end portion of each electrode layer is alternately drawn to both end surfaces in the long side direction of the dielectric layer Ld. The electrode layer Le exposed at one end face is connected to the first lead electrode layer Le1, and the electrode layer Le exposed at the other end face is connected to the second lead electrode layer Le2. The piezoelectric element 322 expands and contracts at a predetermined frequency by applying a predetermined AC voltage between the first and second extraction electrode layers Le1 and Le2, and the diaphragm 321 is vibrated at a predetermined frequency.

  In the configuration example of the piezoelectric element 322 shown in FIGS. 4 and 5, the first extraction electrode layer Le1 is formed from one end surface to the bottom surface of the dielectric layer Ld, and the second extraction electrode layer Le2 is a dielectric layer. It is formed from the other end surface of Ld to the upper surface. The lower surface of the piezoelectric element 322 is joined 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 vibration plate 321 is made of a metal material, but may be made of an insulating material in which the second main surface 32b is covered with a conductive material.

  Therefore, in the present embodiment, as shown in FIG. 2, one of the two wiring members C3, one wiring member C3 (first wiring member) is connected to a terminal portion 324 provided on the diaphragm 321. The other wiring member C <b> 3 (second wiring member) is connected to a terminal portion 325 provided in the piezoelectric element 322. One terminal portion 324 is provided on the second main surface 32b of the diaphragm 321 and the other terminal portion 325 is provided on the second extraction electrode layer Le2 on the upper 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.

  On the other hand, in the configuration example of the piezoelectric element 322 shown in FIGS. 6 and 7, the first extraction electrode layer Le1 is formed from one end surface of the dielectric layer Ld to a part of the upper surface, and the second extraction electrode layer Le2 is formed. Is formed from the other end face of the dielectric layer Ld to another part of the upper surface. In this case, since the two extraction 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 thereon, respectively. In this case, the diaphragm 321 may be made of an insulating material.

  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 attached to the peripheral edge portion 321 c of the diaphragm 321. An adhesive layer that joins the annular member 34 and the support portion 411 may be provided. The internal space of the housing 41 is partitioned by the piezoelectric sounding body 32 into a first space portion S1 and a second space portion S2. The first space S <b> 1 is a space 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 <b> 2 is a space communicating with the sound path 11, and is formed between the piezoelectric sounding body 31 and the bottom of the housing 41.

  The electromagnetic sounding body 31 is assembled on the annular member 34. An adhesive layer is provided between the outer peripheral edge of the electromagnetic sounding body 31 and the side wall 412 of the housing 41 as necessary. Since the adhesive layer also functions as a sealing layer, the sealing degree of the sound field forming space (first space portion S1) of the electromagnetic sounding body 31 can be increased.

[cover]
The cover 42 is fixed to the upper end of the side wall 412 so as to close the inside of the housing 41. On the inner upper surface of the cover 42, there is a pressing portion 421 that presses the electromagnetic sounding body 31 toward the annular member 34. As a result, the annular member 34 is firmly sandwiched between the leg portion 312a of the electromagnetic sounding body 31 and the support portion 411 of the housing 41, so that the peripheral edge portion 321c of the diaphragm 321 is integrated with the housing 41. It becomes possible to connect to.

  The pressing portion 421 of the cover 42 is formed in an annular shape, and the tip portion thereof is an annular upper surface portion 31d (FIGS. 2 and 3) formed around the raised portion 31c of the electromagnetic sounding body 31 via the elastic layer 422. Contact). As a result, the electromagnetic sounding body 31 is pressed with a uniform force over the entire circumference of the annular member 34, and the sounding unit 30 can be properly positioned inside the housing 41. Note that the pressing portion 421 is not limited to being formed in an annular shape, and may be configured by a plurality of pillars.

  A feed-through is provided at a predetermined position of the cover 42 for leading the wiring member C1 connected to the terminal portion 331 of the circuit board 33 to a playback device (not shown).

[Drawer structure of wiring member C3]
In the present embodiment, each wiring member C3 connected to the piezoelectric sounding body 32 is configured to be pulled out from the second main surface 32b side of the diaphragm 321. That is, since the terminal portions 324 and 325 of the piezoelectric sounding body 32 are arranged facing the first space portion S1, a routing path for guiding the wiring member C3 to the terminal portion 333 on the circuit board 33 is provided. Necessary. Therefore, in the present embodiment, guide grooves that can accommodate the wiring members C3 are provided on the side peripheral surface of the base portion 312 of the electromagnetic sounding body 31 and the annular member 34, respectively.

  As shown in FIG. 2, a plurality of wiring members C3 routed between the first surface 31a and the second surface 31b are accommodated in the peripheral surface portion 31e and the upper surface portion 31 of the electromagnetic sounding body 31. A first guide groove 31f is provided. Accordingly, the wiring member C3 is provided between the peripheral surface portion 31e of the electromagnetic sounding body 31 and the side wall portion 412 of the housing 41 and between the upper surface portion 31d of the electromagnetic sounding body 31 and the pressing portion 421 of the cover 42. Can be easily routed without damage.

  The first guide groove 31f is formed along the radial direction in the upper surface portion 31d and along the height direction (Z-axis direction) in the peripheral surface portion 31e. The guide grooves 31f formed in the upper surface portion 31d and the peripheral surface portion 31e are connected to each other. The first guide groove 31f is a square groove, but may be a concave groove having another shape such as a round groove. Although the formation position of the first guide groove 31f is not particularly limited, it is preferably provided at a position close to the terminal portion 333 of the circuit board 33 as shown in FIG.

  In addition, when the pressing part 421 of the cover 42 is composed of a plurality of pillars, the wiring member C3 can be passed between the pillars, so that the formation of the guide grooves 31f on the upper surface part 31d is omitted. Can do.

  On the other hand, the support surface 341 of the annular member 34 is provided with a second guide groove 34a capable of accommodating a plurality of wiring members C3. The second guide groove 34 a is linearly formed in the radial direction so as to communicate 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 communicating with the first guide groove 31 f in a state where the sound generation unit 30 is incorporated in the housing 41. As a result, the wiring member C3 can be easily routed between the legs 312a of the electromagnetic sounding body 31 and the annular member 34 without damaging the wiring member C3.

[Passage]
If the first space portion S1 is sealed, it may be impossible to generate a low-frequency sound wave with a desired frequency characteristic. Specifically, it can flexibly deal with peak level adjustment in a predetermined frequency band and optimization of frequency characteristics at the intersection (cross point) between the characteristic curve in the low frequency range and the characteristic curve in the high frequency range. It becomes difficult.

  Therefore, in the present embodiment, the piezoelectric sounding body 32 is provided with a passage portion 35 that allows communication between the first space portion S1 and the second space portion S2. FIG. 8 is a schematic plan view showing the configuration of the piezoelectric sounding body 32.

  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 a 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, a region for forming the passage portion 35 can be secured without restricting the size of the piezoelectric element 322 more than necessary.

  The passage part 35 is for passing a part of the sound wave generated by the electromagnetic sounding body 31 from the first space part S1 to the second space part S2. Therefore, the frequency characteristics of the bass range 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 desired frequency characteristics of the bass range. The For this reason, the number and size of the passage portions 35 are not limited to the example of FIG. 8. For example, a single passage portion 35 may be provided.

  In addition, the opening shape of the channel | path part 35 is not restricted circularly, The number may differ with places. For example, the passage portion 35 may include an elliptic passage portion 351 as shown in FIG.

[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 wiring member C1. The reproduction signal is input to the electromagnetic sounding body 31 and the piezoelectric sounding body 32 via the circuit board 33 and the wiring members C2 and C3, respectively. 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 in each band is transmitted to the user's ear via the sound path 11. As described above, the earphone 100 functions as a hybrid speaker having a low-frequency sounding body and a high-frequency sounding body.

  Here, the sound wave generated by the electromagnetic sounding body 31 vibrates the vibration plate 321 of the piezoelectric sounding body 32 and propagates to the second space portion S2 and the second space via the passage portion 35. It is formed by a combined wave with a sound wave component propagating to the part S2. Therefore, by optimizing the size and number of the passage portions 35, the low frequency sound wave output from the piezoelectric sounding body 31 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 passage portion 35 is configured by a 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 minimized (shortest). Can be. Thereby, it becomes easy to set a sound pressure peak in a predetermined low sound range.

  For example, FIG. 10 is a characteristic diagram for a reproduced sound wave when the sound wave propagation path becomes longer than necessary. In the figure, the horizontal axis is frequency, the vertical axis is sound pressure (arbitrary unit), F1 is the frequency characteristic of the low frequency range reproduced by the electromagnetic sound generator, and F2 is the high frequency range reproduced by the piezoelectric sound generator. Each frequency characteristic is shown. In the example of FIG. 10, a large dip occurs in the vicinity of about 3 kHz. When the reproduced sound is a music piece, the 3 kHz band generally corresponds to the frequency band of vocal vocal sound. Therefore, when a dip occurs in this band, the vocal sound quality tends to deteriorate.

  On the other hand, FIG. 11 is a characteristic diagram similar to FIG. 10 for the reproduced sound wave when the passage portion 35 is configured with the shortest path. According to this embodiment, a bass frequency characteristic having a peak in the vicinity of 3 kHz can be obtained. Thereby, since the sound quality of vocals is improved, it becomes possible to improve the reproduction quality of music.

  Moreover, the channel | path part 35 has a function as a low-pass filter which cuts a predetermined or more high frequency component among the sound waves generated from the electromagnetic sounding body. This makes it possible to output a sound wave in a predetermined low frequency band without affecting the frequency characteristics of the high sound range generated by the piezoelectric sounding body 32.

  Furthermore, according to the present embodiment, the piezoelectric sounding body 32 is configured to pull out all of the plurality of wiring members C3 to the second main surface 32b side of the diaphragm 321, so the first of the diaphragm 321 is the first. Compared with the case where the wiring is drawn out from the main surface 32a side, not only the workability of connecting the wiring member C3 to the piezoelectric element 322 but also the assembling property to the housing 41 can be improved.

  In addition, since the sounding unit 30 can be integrated into the housing 41 in a state where the electromagnetic sounding body 31 and the piezoelectric sounding body 32 are connected to each other by the wiring member C3, the assembling performance is further improved. Improvements can be made. Further, since the first and second guide grooves 31f and 34a capable of accommodating the wiring member C3 are provided on the peripheral surface portion 31e of the electromagnetic sounding body 31 and the support surface 341 of the annular member 34, the wiring member C3 is provided. It can be routed through an appropriate route without being damaged. As a result, stable assembly accuracy can be ensured without requiring skill of work.

<Second Embodiment>
In the above-described piezoelectric sounding body 32, the relative position between the diaphragm 321 and the piezoelectric element 322 is important in securing a desired resonance mode of the diaphragm 321. Therefore, the piezoelectric sounding body 32 of this embodiment has a positioning structure of the piezoelectric element 322 with respect to the diaphragm 321.

  FIG. 12 is a schematic plan view showing the configuration of the piezoelectric sounding body 32 of the present embodiment. Hereinafter, configurations different from those of the first embodiment will be mainly described, and configurations similar to those of the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted or simplified.

  As shown in FIG. 12, the center of the diaphragm 321 and the center of the piezoelectric element 322 coincide with each other, and these centers correspond to the center (or center of gravity) 32c of the piezoelectric power generation body 32. Positioning of the piezoelectric element 322 in the circumferential direction (rotating direction around the center 32c) with respect to the diaphragm 321 is set with reference to a reference point 321s formed at a part of the peripheral edge of the diaphragm 321. The reference point 321s may be a notch or a recessed portion such as an emboss formed in a part of the peripheral edge of the diaphragm 321, or some mark that is stamped or printed.

  Since the piezoelectric element 322 is formed in a rectangular shape having a short side portion and a long side portion, the piezoelectric element 322 has a posture in which the center of the long side portion faces the reference point 321s as shown in FIG. Then, it is joined to the diaphragm 321. However, the present invention is not limited to this, and the center of the short side portion of the piezoelectric element 322 may be set so as to face the reference point 321s. Or you may use a part of channel | path part 35 as a reference point, without providing the reference point 321s separately.

  In the example of FIG. 12, since the piezoelectric element 322 has two long sides, the degree of freedom of arrangement of the piezoelectric element 322 cannot be limited to one. Therefore, as shown in FIG. 13, if a tapered portion 322 s is provided at one corner of the piezoelectric element 322, the degree of freedom of arrangement of the piezoelectric element 322 with respect to the diaphragm 321 can be limited to one.

  Further, the formation of the tapered portion 322s makes it easy to identify the orientation of the piezoelectric element 322 even before the formation of the external electrode layers (leading electrode layers Le1, Le2). Thereby, since an appropriate formation process of the external electrode layer is ensured, the productivity of the piezoelectric sounding body 32 can be increased.

  As described above, according to the present embodiment, since the piezoelectric element 322 can be properly positioned with respect to the diaphragm 321, the vibration of the piezoelectric sounding body 32 in a predetermined resonance mode can be secured. Thus, a high-frequency sound wave having a desired frequency characteristic can be reproduced.

  Further, according to the present embodiment, since the diaphragm 321 has the predetermined reference point 321 s, the diaphragm 321 can be positioned in the circumferential direction with respect to the housing 41. Furthermore, by providing the piezoelectric element 322 with a reference point such as the tapered portion 322s, the positioning accuracy of the piezoelectric element with respect to the diaphragm 321 can be increased, the external electrode layer can be formed, and the wiring member C3 to the piezoelectric element 322 can be formed. Thus, it is possible to appropriately perform the wire connection work, and it is possible to improve the productivity of the piezoelectric power generation body 32.

<Third Embodiment>
FIG. 14 is a schematic cross-sectional view of an earphone 200 according to another embodiment of the present invention. Hereinafter, configurations different from those of the first embodiment will be mainly described, and configurations similar to those of the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted or simplified.

  The earphone 200 of the present embodiment differs from the first embodiment described above in the configuration of the sound generation unit 50, particularly the piezoelectric sounding body 52. The piezoelectric sounding body 52 includes a vibration plate 521 and a piezoelectric element 322 bonded to one main surface of the vibration plate 521 (in this example, a main surface facing the first space portion S1).

  FIG. 15 is a schematic plan view showing the configuration of the piezoelectric sounding body 52. As shown in FIG. 15, a plurality of (three in the illustrated example) protruding pieces 521 g protruding radially outward are provided on the peripheral edge of the diaphragm 521. The plurality of protruding pieces 521g are fixed to the inner peripheral portion of the annular member 34. Therefore, the diaphragm 521 is fixed to the support portion 411 of the housing 41 through the plurality of protruding pieces 531g and the annular member 34.

  The plurality of protruding pieces 521g are typically formed at equiangular intervals. The plurality of protruding pieces 521g are formed by providing a plurality of notches 521h at the peripheral edge of the diaphragm 521. The protruding amount of the protruding piece 521g is adjusted by the notch depth of the notch 521h.

  The piezoelectric sounding body 52 is provided with a passage portion 55 that allows communication between the first space portion S1 and the second space portion S2. In the present embodiment, the notch depth of each notch 521h is formed so that an arc-shaped opening having a predetermined width is formed between the inner peripheral surface of the annular member 34 and a plurality of adjacent protruding pieces 521g. Is set. By the opening, a passage portion 55 penetrating in the thickness direction of the diaphragm 521 is formed.

  The number of the 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 appropriately set according to the desired low frequency range frequency characteristics. It is determined. As a result, similarly to the first embodiment, it is possible to obtain frequency characteristics of reproduced sound having a sound pressure peak in a predetermined low frequency range (for example, 3 kHz), for example. 16 shows a configuration example of the diaphragm 521 having four protruding pieces 521g, and FIG. 17 shows a configuration example of the diaphragm 521 having five protruding pieces 521g.

  In addition, since the diaphragm 521 of this embodiment is configured to vibrate with some or all of the plurality of protrusions 521g as fulcrums, the resonance of the diaphragm 521 depends on the number, shape, arrangement, or fixing method of the protrusions 521g. The frequency can be adjusted. For example, when the resonance frequency of the diaphragm 521 having four fulcrums as shown in FIG. 16 is designed to be 10 kHz, the resonance frequency of the diaphragm 521 having three fulcrums as shown in FIG. 15 is as low as 8 kHz, for example. Thus, the resonance frequency of the diaphragm 521 having five fulcrums as shown in FIG. 17 is as high as 12 kHz, for example. In addition, the resonance frequency can be adjusted by the thickness, outer diameter, material, and the like of the diaphragm 521.

  As described above, the resonance frequency of the diaphragm 521 can be adjusted by the number of the protrusions 521g and the like. For example, the characteristic curve of the low range by the electromagnetic sounding body 31 and the high frequency range by the piezoelectric sounding body 52 can be adjusted. Desired frequency characteristics can be easily realized, for example, by flattening the composite frequency at the intersection (cross point) with the characteristic curve.

  18A to 18C are schematic diagrams for explaining the relationship between the resonance frequency of the diaphragm 521 and the frequency characteristics of the reproduced sound of the earphone 200, where the horizontal axis indicates the frequency and the vertical axis indicates the sound pressure. In each figure, F1 (thin solid line) indicates the low frequency range and frequency characteristics reproduced by the electromagnetic sounding body 31, F2 (dashed line) indicates the frequency characteristics of the high frequency range reproduced by the piezoelectric sounding body 52, and F0 (thick solid line) indicates these combined characteristics. Further, P indicates an intersection of the curve F1 and the curve F2, that is, the cross point.

  18A to 18C, the resonance frequency of the diaphragm 521 increases in the order of B, C, and A. In the example of FIG. 18A, a dip is likely to occur in the band of the cross point P, and in the example of FIG. On the other hand, in the example of FIG. 18C, a flat characteristic is obtained in the band of the cross point P.

  In general, in a hybrid speaker, a cross point between a characteristic curve in a low sound region and a characteristic curve in a high sound region is important for tuning the sound quality. Typically, as shown in FIG. 18C, the composite frequency of the low sound range and the high sound 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 fulcrums (projecting pieces 521g) of the diaphragm 521, a desired frequency characteristic that makes the band of the cross point P flat is obtained. It can be easily realized.

  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 hybrid speaker provided with the electromagnetic sounding body 31 and the piezoelectric sounding body 32 has been described as an example. However, the present invention also applies to an electroacoustic transducer having only a piezoelectric sounding body. Is applicable.

  In the above embodiment, the passage portion for guiding the sound wave in the low frequency range to the sound path is provided in the piezoelectric sounding body. However, the present invention is not limited to this and may be provided around the piezoelectric sounding body. In this case, for example, as schematically shown in FIG. 19, the outer diameter of the piezoelectric sounding body U2 is formed smaller than the inner diameter of the side wall portion of the casing B, and the electromagnetic sounding body U1 is generated therebetween. A passage portion T that allows the sound waves in the low frequency range to pass therethrough is formed. The piezoelectric sounding body U2 is fixed to the bottom B1 of the housing B via a plurality of columns R. Thereby, the sound wave which passed the channel | path part T can be guide | induced to the sound path B2.

  In the hybrid speaker, the earphone 100 including the passage portion 35 that allows the first space portion S1 and the second space portion S2 to communicate with each other has been described as an example. However, the passage portion 35 is not necessarily provided. It does not have to be.

  Although the earphones 100 and 200 have been described as examples of the electroacoustic transducer, the present invention is not limited to this, and the present invention is applicable to headphones and hearing aids. The present invention can also be applied as a speaker unit mounted on an electronic device such as a portable information terminal or a personal computer.

DESCRIPTION OF SYMBOLS 10 ... Earphone main body 30 ... Sound production unit 31 ... Electromagnetic sound producing body 32 ... Piezoelectric sound producing body 34 ... Ring member 41 ... Housing 321 ... Diaphragm 322 ... Piezoelectric element C3 ... Wiring member

Claims (18)

  A housing,
  A diaphragm having one main surface and the other main surface opposite to the one main surface, and directly or indirectly supported by the housing, and a piezoelectric layer and a plurality of electrode layers are laminated. A piezoelectric element having a structure and a piezoelectric element joined to the one main surface of the diaphragm, and
  A plurality of wiring members electrically connected to the plurality of electrode layers and led out from the piezoelectric element to the one main surface side of the diaphragm;
  An electromagnetic sounding body having a first surface facing the one main surface and a vibrating body and housed in the housing;
  An electroacoustic transducer comprising: The electroacoustic transducer according to claim 1,
The planar shape of the diaphragm is circular,
The planar shape of the piezoelectric element is a polygonal shape.
Electroacoustic transducer . The electroacoustic transducer according to claim 1 or 2,
The one main surface of the diaphragm is made of a conductive material,
The plurality of electrode layers include a first electrode layer electrically connected to the one main surface, and a second electrode layer,
The plurality of wiring members include a first wiring member connected to the one main surface and a second wiring member connected to the second electrode layer.
Electroacoustic transducer . The electroacoustic transducer according to claim 1 or 2,
The plurality of electrode layers include a first electrode layer and a second electrode layer adjacent to each other on the surface of the piezoelectric element,
The plurality of wiring members include a first wiring member connected to the first electrode layer and a second wiring member connected to the second electrode layer.
Electroacoustic transducer . The electroacoustic transducer according to any one of claims 2 to 4,
The piezoelectric element is formed in a rectangular shape having a short side and a long side.
Electroacoustic transducer . The electroacoustic transducer according to any one of claims 2 to 4,
The piezoelectric element has a polygonal shape with notches formed in corners.
Electroacoustic transducer . The electroacoustic transducer according to claim 5 or 6,
The diaphragm has a reference point that defines a relative positional relationship with the piezoelectric element.
Electroacoustic transducer . The electroacoustic transducer according to any one of claims 1 to 7 ,
Wherein the housing includes a support portion for supporting the peripheral portion of the diaphragm directly or indirectly, the diaphragm and the electroacoustic transducer that having a side wall portion surrounding said electromagnetic sounding body. The electroacoustic transducer according to claim 8 ,
The electromagnetic sounding body is:
A peripheral surface portion fitted to the side wall portion;
An electroacoustic transducer having a first guide groove that is provided in the peripheral surface portion and accommodates the plurality of wiring members that are routed to the opposite side of the first surface. The electroacoustic transducer according to claim 9 ,
An annular member interposed between the diaphragm and the electromagnetic sounding body;
The annular member is
A support surface for supporting the electromagnetic sounding body;
An electroacoustic transducer having a second guide groove provided on the support surface, communicating with the first guide groove and accommodating the plurality of wiring members. The electroacoustic transducer according to any one of claims 1 to 10 ,
An electroacoustic transducer having a pressing portion that presses the electromagnetic sounding body toward the support portion, and further comprising a cover that seals the housing. The electroacoustic transducer according to any one of claims 1 to 11 ,
Further comprising a substrate having a terminal portion connected to the plurality of wiring members,
The electromagnetic sounding device further includes a second surface formed on a side opposite to the first surface and provided with the substrate.   The electroacoustic transducer according to any one of claims 1 to 12,
  The piezoelectric sounding body divides the interior of the housing into a first space and a second space,
  The electromagnetic sounding body is disposed in the first space portion,
  The electroacoustic transducer further includes a passage portion that is provided around the piezoelectric sounding body or the piezoelectric sounding body and communicates between the first space portion and the second space portion.
  Electroacoustic transducer.   The electroacoustic transducer according to claim 13,
  The passage portion is provided in a thickness direction of the diaphragm.
  Electroacoustic transducer.   The electroacoustic transducer according to claim 14,
  The passage portion is composed of one or a plurality of through holes provided in the diaphragm.
  Electroacoustic transducer.   The electroacoustic transducer according to claim 15,
  The opening shape of the through hole is circular or elliptical.
  Electroacoustic transducer.   The electroacoustic transducer according to any one of claims 13 to 16, wherein
  The planar shape of the piezoelectric element is a polygonal shape,
  The passage portion is provided in a region between a side portion of the piezoelectric element and a peripheral portion of the diaphragm.
  Electroacoustic transducer.   The electroacoustic transducer according to claim 14,
  The passage portion is composed of a plurality of notches formed in a peripheral portion of the diaphragm.
  Electroacoustic transducer.

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