JP2014049992A - Acoustic generator, acoustic generation device and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acoustic generator, an acoustic generation device and electronic equipment capable of suppressing the frequency fluctuation of a sound pressure as much as possible by reducing a difference between a resonance peak in the frequency characteristics of a sound pressure and a dip (valley between resonance peaks), and improving sound quality.SOLUTION: An acoustic generator includes: a vibrator; and a piezoelectric vibration element. The piezoelectric vibration element is disposed on the vibrator. Also, the piezoelectric vibration element has a protrusion on at least a part of the surface.

Description

  Embodiments of the disclosure relate to a sound generator, a sound generation device, and an electronic apparatus.

  Conventionally, it is known that an acoustic generator typified by a piezoelectric speaker can be used as a small and thin speaker. Such a sound generator can be used as a speaker incorporated in an electronic device such as a mobile phone or a thin television.

  As an acoustic generator, for example, there is one including a vibrating body and a piezoelectric vibrating element provided on the vibrating body (see, for example, Patent Document 1). This is a configuration in which a vibrating body is vibrated by a piezoelectric vibration element, and a sound is generated using a resonance phenomenon of the vibrating body.

Japanese Patent Laid-Open No. 2004-23436

  However, in the configuration in which sound pressure is generated by resonance of the vibrating body itself as in the acoustic generator described above, the sound pressure is reduced due to the difference between the resonance peak and the dip (valley between resonance peaks) in the frequency characteristics of the sound pressure. There was a risk of frequency fluctuations. And this may hinder improvement in sound quality.

  One aspect of the embodiment has been made in view of the above, and reduces the difference between the resonance peak and the dip in the frequency characteristic of the sound pressure to suppress the frequency fluctuation of the sound pressure as much as possible, thereby improving the sound quality. An object is to provide a sound generator, a sound generator, and an electronic device that can be improved.

  An acoustic generator according to an aspect of an embodiment includes a vibrating body and a piezoelectric vibrating element provided on the vibrating body. The piezoelectric vibration element has a protrusion on at least a part of its surface.

  According to the acoustic generator of one aspect of the embodiment, the piezoelectric vibration element has a protrusion on at least a part of the surface, thereby reducing the difference between the resonance peak and the dip in the frequency characteristic of the sound pressure and reducing the sound pressure. The frequency variation can be suppressed as much as possible, and the sound quality can be improved.

FIG. 1A is a schematic plan view of the sound generator according to the first embodiment. 1B is a cross-sectional view taken along line A-A ′ of FIG. 1A. 1C is a cross-sectional view taken along line B-B ′ of FIG. 1A. FIG. 2 is an enlarged cross-sectional view taken along line B-B ′ of FIG. 1A, showing an acoustic generator according to a modification example of the first embodiment. FIG. 3 is an enlarged cross-sectional view taken along line B-B ′ of FIG. 1A, showing an acoustic generator according to another modification example of the first embodiment. FIG. 4 is a schematic plan view of an acoustic generator according to another modification example of the first embodiment. FIG. 5 is a block diagram of the sound generator. FIG. 6 is a block diagram of the electronic device. FIG. 7 is an enlarged cross-sectional view taken along line B-B ′ of FIG. 1A, showing an acoustic generator according to the second embodiment. FIG. 8 is an enlarged cross-sectional view taken along the line B-B ′ of FIG. 1A, showing an acoustic generator according to a modification example of the second embodiment. FIG. 9 is an enlarged cross-sectional view taken along line B-B ′ of FIG. 1A, showing an acoustic generator according to another modification example of the second embodiment. FIG. 10 is a cross-sectional view taken along the line A-A ′ of FIG. 1A, illustrating an acoustic generator according to a modification example of the first embodiment. FIG. 11 is a cross-sectional view taken along line A-A ′ of FIG. 1A, illustrating an acoustic generator according to a modification example of the first embodiment. FIG. 12 is a schematic plan view of an acoustic generator according to a modification example of the first embodiment.

  Hereinafter, embodiments of a sound generator, a sound generator, and an electronic device disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

(First embodiment)
1A is a schematic plan view of the sound generator 1 according to the first embodiment viewed from a direction perpendicular to the main surface of the vibrating body 10, FIG. 1B is a cross-sectional view taken along the line AA ′ of FIG. 1A, and FIG. FIG. 1B is a sectional view taken along line BB ′ in FIG. 1A. In FIG. 1B and FIG. 1C, in order to facilitate understanding, the sound generator 1 is shown expanded and deformed in the vertical direction.

  As shown in FIGS. 1A to 1C, the sound generator 1 according to the first embodiment includes a vibrating body 10, a piezoelectric vibrating element 20, and a frame body 30. Such an acoustic generator 1 is called a so-called piezoelectric speaker, and generates a sound pressure using a resonance phenomenon of the vibrating body 10 itself.

  The vibrating body 10 can be formed using various materials such as resin, metal, and paper. For example, the thin plate-like vibrating body 10 can be formed of a resin film such as polyethylene, polyimide, or polypropylene having a thickness of about 10 to 200 μm. Since the resin film is a material having a lower elastic modulus and mechanical Q value than a metal plate or the like, the vibrating body 10 is made of a resin film to bend and vibrate the vibrating body 10 with a large amplitude so that the sound pressure is reduced. It is possible to reduce the difference between the resonance peak and the dip by widening the width of the resonance peak and reducing the height in the frequency characteristics.

  The piezoelectric vibration element 20 is a bimorph laminated piezoelectric vibration element. For example, the piezoelectric vibration element 20 includes a laminated body 21, surface electrode layers 22 and 23 formed on the upper and lower surfaces of the laminated body 21, and an external surface formed on the side surface where the end face of the internal electrode layer 24 of the laminated body 21 is exposed. Electrodes 25 and 26 are provided. Then, lead terminals 27 a and 27 b are connected to the external electrodes 25 and 26.

  The laminate 21 is formed by alternately laminating four piezoelectric layers 28a, 28b, 28c, 28d made of ceramics and three internal electrode layers 24. The piezoelectric vibration element 20 has a rectangular main surface on the upper surface side and the lower surface side, and the piezoelectric layers 28a and 28b and the piezoelectric layers 28c and 28d are alternately polarized in the thickness direction.

  Therefore, when a voltage is applied to the piezoelectric vibration element 20 via the lead terminals 27a and 27b, for example, the lower surface side of the piezoelectric vibration element 20, in other words, the piezoelectric layers 28c and 28d on the vibration body 10 side contract, while the upper surface The piezoelectric layers 28a and 28b on the side are deformed so as to extend. As described above, the piezoelectric layers 28a and 28b on the upper surface side of the piezoelectric vibration element 20 and the piezoelectric layers 28c and 28d on the lower surface side exhibit opposite expansion and contraction behavior, and as a result, the piezoelectric vibration element 20 is bent bimorph-shaped. By vibrating, a certain vibration can be given to the vibrating body 10 to generate a sound.

  As described above, the piezoelectric vibration element 20 is a bimorph-type laminated piezoelectric vibration element, and the piezoelectric vibration element 20 itself bends and vibrates independently. Therefore, the piezoelectric vibration element 20 is, for example, the soft vibration body 10 regardless of the material of the vibration body 10. However, strong vibration can be generated, and a sufficient sound pressure can be obtained with a small number of piezoelectric vibrators 20.

  Here, as the material constituting the piezoelectric layers 28a, 28b, 28c, 28d, conventionally, lead-free piezoelectric materials such as lead zirconate titanate (PZT), Bi layered compounds, tungsten bronze structure compounds, etc. The used piezoelectric ceramics can be used.

  The material of the internal electrode layer 24 preferably contains a metal component made of silver and palladium and a material component constituting the piezoelectric layers 28a, 28b, 28c, 28d. When the internal electrode layer 24 contains the ceramic component constituting the piezoelectric layers 28a, 28b, 28c, 28d, the difference in thermal expansion between the piezoelectric layers 28a, 28b, 28c, 28d and the internal electrode layers 24, 24, 24. Thus, it is possible to obtain the piezoelectric vibration element 20 in which the stress due to the above is reduced.

  Further, as the wiring connected to the lead terminals 27a and 27b, in order to reduce the height of the piezoelectric vibration element 20, it is preferable to use a flexible wiring in which a metal foil such as copper or aluminum is sandwiched between resin films.

  Furthermore, as shown in FIGS. 1A and 1C, the piezoelectric vibration element 20 has protrusions 29a and 29b on at least a part of its surface, thereby reducing the difference between the resonance peak and the dip in the frequency characteristics of sound pressure. Therefore, the frequency variation of the sound pressure is suppressed as much as possible to improve the sound quality.

  More specifically, the piezoelectric vibration element 20 has a plurality of, for example, two protrusions 29a and 29b. The plurality of protrusions 29a and 29b are disposed on the side surface 20a2 (for example, the upper and lower side surfaces 20a2 in FIG. 1A) adjacent to the surface 20a1 facing the vibrating body 10 of the piezoelectric vibration element 20. The protrusions 29a and 29b are provided on the laminated body 21 including, for example, the internal electrode layer 24 and the piezoelectric layers 28a, 28b, 28c, and 28d, and protrude outward from the side surface 20a2, that is, apart from the side surface 20a2. It is formed to protrude in the direction of

  As described above, since the piezoelectric vibration element 20 has the protrusions 29a and 29b on at least a part of its surface, the symmetry of the piezoelectric vibration element 20 is lowered. Therefore, in the piezoelectric vibration element 20, the resonance frequency is dispersed by the protrusions 29a and 29b, and the peak shape of the sound pressure at the resonance frequency of the vibrating body 10 can be made smooth over a wide frequency range. As a result, the difference between the resonance peak and the dip in the frequency characteristic of the sound pressure can be reduced to suppress the frequency variation of the sound pressure as much as possible, and the sound quality can be improved.

  The protrusions 29a and 29b are disposed in the side surface 20a2 of the piezoelectric vibration element 20 near the lower end in FIG. 1C, in other words, near the surface 20a1 facing the vibrating body 10. More preferably, the protrusions 29a and 29b are arranged at the ridge line portion or the apex portion of the side surface 20a2 of the piezoelectric vibration element 20.

  Explaining this, in the side surface 20a2 of the piezoelectric vibration element 20, in the vicinity of the surface 20a1 facing the vibrating body 10, and further on the ridge line portion between the side surface 20a2 and the surface 20a1 facing the vibrating body 10, particularly the vertex portion, Stress due to vibration of the piezoelectric vibration element 20 itself tends to concentrate. Therefore, by providing the protrusions 29a and 29b as described above, the strength of the ridge line portion and the vertex portion can be improved, and the durability of the piezoelectric vibration element 20 itself can be improved.

  Further, the protrusions 29 a and 29 b disposed in the vicinity of the surface 20 a 1 facing the vibrating body 10 are embedded in an adhesive 40 that bonds the piezoelectric vibrating element 20 to the vibrating body 10. Thus, by embedding the protrusions 29 a and 29 b in the adhesive 40, a so-called anchor effect that improves the bonding strength between the piezoelectric vibration element 20 and the vibrating body 10 can be obtained. Thereby, the piezoelectric vibration element 20 becomes difficult to peel from the vibrating body 10, and as a result, the durability of the acoustic generator 1 can be improved.

  The tips 29a1 and 29b1 of the protrusions 29a and 29b are formed at an acute angle. Thereby, since the protrusions 29a and 29b are fixed in a state of being pierced into the adhesive 40, the bonding strength between the piezoelectric vibration element 20 and the vibrating body 10 can be further improved.

  Further, the protrusions 29a and 29b have asymmetric shapes with respect to the center C of the piezoelectric vibration element 20 as well shown in FIG. 1C. That is, when the shape of the protrusion 29a is compared with the shape of the protrusion 29b, the protrusions 29a and 29b have shapes that do not have symmetry such as rotational symmetry or mirror symmetry with respect to the center C of the piezoelectric vibration element 20. It has become.

  As a result, the resonance frequency of the piezoelectric vibration element 20 itself that is the vibration source can be further dispersed as compared with the case where the shapes of the protrusions 29a and 29b are made symmetric, and the difference between the resonance peak and the dip is further increased. It can be further reduced to suppress the frequency variation of the sound pressure.

  The piezoelectric vibration element 20 configured as described above is bonded to one surface 10a (hereinafter referred to as the upper surface 10a) of the vibrating body 10 via an adhesive 40. The thickness of the adhesive 40 between the piezoelectric vibration element 20 and the vibrating body 10 is relatively thin, for example, 20 μm or less. Thus, when the thickness of the adhesive 40 is 20 μm or less, the vibration of the laminated body 21 can be easily transmitted to the vibrating body 10.

  As the adhesive 40, for example, a known material such as an epoxy resin, a silicon resin, or a polyester resin can be used, but the adhesive is not limited thereto. In addition, as a method for curing the resin used for the adhesive 40, any method such as thermosetting, photocuring, and anaerobic curing may be used.

  The frame body 30 plays a role of holding the vibrating body 10 and forming a fixed end of vibration. For example, as shown in FIG. 1B and FIG. 1C, the frame body 30 is configured by joining a rectangular upper frame member 30 a and a lower frame member 30 b in the vertical direction. And the outer peripheral part of the vibrating body 10 is pinched | interposed between the upper frame member 30a and the lower frame member 30b, and it fixes in the state which provided predetermined tension. Therefore, the acoustic generator 1 including the vibrating body 10 with less deformation such as deflection even when used for a long time is obtained.

  Although the thickness and material of the frame 30 are not particularly limited, in the present embodiment, for example, a stainless steel material having a thickness of 100 to 1000 μm is used because of excellent mechanical strength and corrosion resistance.

  In the acoustic generator 1, as shown in FIGS. 1B and 1C, the piezoelectric vibration element 20 and the upper surface 10a of the vibrating body 10 are covered with a coating layer 50 made of resin. Specifically, the coating layer 50 is configured to cover the piezoelectric vibration element 20 and the like by pouring resin into the frame of the upper frame member 30a of the frame body 30. In FIG. 1A, the covering layer 50 is not shown for easy understanding.

  The resin forming the coating layer 50 is, for example, an epoxy resin, an acrylic resin, a silicon resin, or rubber, but these are examples and are not limited. Thus, by covering the piezoelectric vibration element 20 with the coating layer 50, an appropriate damping effect can be induced, and the difference between the resonance peak and the dip can be suppressed as well as the resonance phenomenon can be suppressed. preferable. Furthermore, the piezoelectric vibration element 20 can be protected from the external environment.

  In the acoustic generator 1 according to the present embodiment, the entire upper surface 10a of the vibrating body 10 is covered with the coating layer 50, but it is not necessary to cover the entire surface. That is, the acoustic generator 1 only needs to cover the piezoelectric vibrating element 20 and at least a part of the upper surface 10a of the vibrating body 10 on which the piezoelectric vibrating element 20 is provided with the coating layer 50.

  As described above, in the first embodiment, in the acoustic generator 1, the piezoelectric vibration element 20 has the protrusions 29 a and 29 b on at least a part of the surface thereof, so that the resonance peak and dip in the frequency characteristics of the sound pressure are obtained. The frequency variation of the sound pressure can be suppressed as much as possible, and the sound quality can be improved.

  Here, with reference to FIG. 2, the sound generator 1 which concerns on the modification in this embodiment is demonstrated. FIG. 2 is an enlarged cross-sectional view taken along the line B-B ′ of FIG. 1A, showing an enlarged vicinity of the joint portion between the piezoelectric vibrating element 20 and the vibrating body 10. 2 and other enlarged cross-sectional views taken along the line BB ′ described below, the piezoelectric vibration element 20 is simplified and the adhesive 40 is also expanded in the vertical direction for easy understanding. It is shown as deformed. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 2, the piezoelectric vibration element 20 of the acoustic generator 1 according to the modification has a plurality of, for example, four protrusions 29a, 29b, 29c, and 29d. Four protrusions 29a, 29b, 29c, and 29d are arranged on the side surface 20a2 of the piezoelectric vibration element 20 two by two.

  Specifically, the protrusions 29a and 29b are disposed in the vicinity of the surface 20a1 facing the vibrating body 10 in the side surface 20a2, while the protrusions 29c and 29d are disposed in the vicinity of the surface 20a3 opposite to the facing surface 20a1. The

  Since the acoustic generator 1 according to this modification is configured as described above, the difference between the resonance peak and the dip is reduced even when the number of the protrusions 29a, 29b, 29c, and 29d is four. The frequency variation of the sound pressure can be suppressed as much as possible.

  The plurality of protrusions 29 a, 29 b, 29 c, and 29 d are asymmetric with respect to the center C of the piezoelectric vibration element 20. As a result, the resonance frequency of the piezoelectric vibration element 20 can be dispersed as compared with the case where the shapes of the protrusions 29a, 29b, 29c, and 29d are made symmetric, and the difference between the resonance peak and the dip is further reduced. Thus, the frequency variation of the sound pressure can be suppressed.

  Further, the tips 29c1 and 29d1 of the protrusions 29c and 29d are formed at an acute angle like the protrusions 29a and 29b. Thereby, since the protrusions 29c and 29d are fixed in a state of being pierced into the covering layer 50, the piezoelectric vibration element 20 becomes difficult to move even when a force is applied by an impact from the outside, for example. The durability of the generator 1 can be further improved.

  In FIG. 2, the protrusions 29a, 29b, 29c, and 29d are arranged in both the vicinity of the surface 20a1 facing the vibrating body 10 and the vicinity of the surface 20a3 on the opposite side. Instead, it may be arranged only in the vicinity of the opposite surface 20a3.

  FIG. 3 is an enlarged cross-sectional view taken along line B-B ′ of FIG. 1A, showing an acoustic generator 1 according to another modification example of the present embodiment. As shown in FIG. 3, the piezoelectric vibration element 20 of the acoustic generator 1 according to this modification has a plurality of, for example, two protrusions 29b and 29e. The plurality of protrusions 29b and 29e are disposed on the side surface 20a2.

  The plurality of protrusions 29 b and 29 e are disposed asymmetrically with respect to the center C of the piezoelectric vibration element 20. That is, in FIG. 3, the right protrusion 29b is arranged so as to be continuous from the lower end of the side face 20b, whereas the left protrusion 29e is arranged at a position spaced upward by a predetermined distance from the lower end of the side face 20b. . As a result, the resonance frequency of the piezoelectric vibration element 20 itself can be dispersed compared to the case where the protrusions 29b and 29e are arranged with symmetry, and the difference between the resonance peak and the dip is further reduced. The frequency fluctuation of the pressure can be suppressed as much as possible.

  In the acoustic generator 1 according to the first embodiment, the protrusions 29a and 29b are arranged on the entire upper and lower surfaces in FIG. 1A of the side surface 20a2 of the piezoelectric vibration element 20, for example, as shown in FIG. As described above, the side surface 20a2 is disposed at positions that are asymmetric with respect to the center C of the piezoelectric vibration element 20, particularly at positions that do not have symmetry such as rotational symmetry or mirror symmetry on the surface along the vibration surface of the piezoelectric vibration element 20. You may be made to do. Even with such a configuration, it is possible to further reduce the difference between the resonance peak and the dip and suppress the frequency variation of the sound pressure as much as possible.

  Further, as shown in FIG. 5, the sound generator 2 can be configured by housing the sound generator 1 having the above-described configuration in a resonance box 200. The resonance box 200 is a housing that houses the sound generator 1, and resonates the sound emitted from the sound generator 1 and radiates it as sound waves from the housing surface. Such a sound generator 2 can be used alone as a speaker, and can be suitably incorporated into various electronic devices 3, for example.

  As described above, since the difference between the resonance peak and the dip in the frequency characteristic of sound pressure, which is disadvantageous in the piezoelectric speaker, can be reduced, the sound generator 1 according to the present embodiment can be used for a mobile phone or a thin television. Alternatively, it can be suitably incorporated into the electronic device 3 such as a tablet terminal.

  Note that the electronic device 3 to which the sound generator 1 can be incorporated is not limited to the above-described mobile phone, flat-screen TV, tablet terminal, and the like. Conventionally, home appliances that have not been focused on sound quality are also included.

  Here, the electronic device 3 including the above-described sound generator 1 will be briefly described with reference to FIG. FIG. 6 is a block diagram of the electronic device 3. The electronic device 3 includes the acoustic generator 1 described above, an electronic circuit connected to the acoustic generator 1, and a housing 300 that houses the acoustic generator 1 and the electronic circuit.

  Specifically, as illustrated in FIG. 6, the electronic device 3 accommodates an electronic circuit including a control circuit 301, a signal processing circuit 302, a wireless circuit 303 as an input device, an antenna 304, and these. And a housing 300. Although the wireless input device is shown in FIG. 6, it can be provided as a signal input by normal electric wiring.

  In addition, description was abbreviate | omitted here about the other electronic members (for example, devices and circuits, such as a display, a microphone, and a speaker) with which the electronic device 3 is provided. Moreover, in FIG. 6, although one acoustic generator 1 was illustrated, two or more acoustic generators 1 and other transmitters can be provided.

  The control circuit 301 controls the entire electronic device 3 including the wireless circuit 303 via the signal processing circuit 302. An output signal to the sound generator 1 is input from the signal processing circuit 302. Then, the control circuit 301 generates a sound signal S by controlling the signal processing circuit 302 from the signal input to the radio circuit 303 and outputs the sound signal S to the sound generator 1.

  In this way, the electronic device 3 shown in FIG. 6 incorporates the small and thin acoustic generator 1 and reduces the difference between the resonance peak and the dip as much as possible to suppress the frequency variation of the sound pressure. However, it is possible to improve the sound quality as a whole even in the high sound region including the low sound region having a low frequency.

  6 exemplifies the electronic apparatus 3 in which the sound generator 1 is directly mounted as the sound output device. However, as the sound output device, for example, the sound generator 2 in which the sound generator 1 is housed in the housing is mounted. It may be the configuration.

(Second Embodiment)
FIG. 7 is an enlarged cross-sectional view taken along the line BB ′ of FIG. 1A, in which the vicinity of the joint portion between the piezoelectric vibrating element 20 and the vibrating body 10 is enlarged in the acoustic generator 1 according to the second embodiment. As shown in FIG. 7, in the acoustic generator 1 according to the second embodiment, the piezoelectric vibration element 20 has a plurality of, for example, two protrusions 29f and 29g. The plurality of protrusions 29f and 29g are disposed on the surface 20a1 facing the vibrating body 10 of the surface of the piezoelectric vibration element 20, and are formed so as to protrude from the surface 20a1 toward the vibrating body 10.

  Therefore, even in the acoustic generator 1 according to the second embodiment, as in the first example, the symmetry of the piezoelectric vibration element 20 is reduced. In the piezoelectric vibration element 20, the resonance frequency is increased by the protrusions 29f and 29g. Can be distributed and the sound pressure peak at the resonance point can be made smooth. Thereby, the difference between the resonance peak and the dip in the frequency characteristic of the sound pressure can be reduced, and the frequency variation of the sound pressure can be suppressed as much as possible. The remaining configuration and effects are the same as those in the first embodiment, and a description thereof will be omitted.

  Next, an acoustic generator 1 according to a modification of the second embodiment will be described with reference to FIG. FIG. 8 is an enlarged cross-sectional view taken along the line B-B ′ of FIG. 1A, showing an enlarged vicinity of the joint portion between the piezoelectric vibration element 20 and the vibrating body 10.

  As shown in FIG. 8, the piezoelectric vibration element 20 according to the modification has a plurality of, for example, two protrusions 29h and 29i. The plurality of protrusions 29h and 29i are disposed on the surface 20a3 opposite to the surface 20a1 facing the vibrating body 10, and are formed to protrude outward from the surface 20a3. Further, the tips 29h1 and 29i1 of the protrusions 29h and 29i are formed at an acute angle.

  Thereby, since the protrusions 29h and 29i are fixed in a state of being pierced into the covering layer 50, the piezoelectric vibration element 20 becomes difficult to move even when a force is applied by an impact or the like from the outside, for example. The durability of the generator 1 can be further improved.

  Note that, as shown in FIG. 9, the above-described effect can be obtained in the same manner even when the above-described protrusions 29f, 29g, 29h, and 29i are all arranged on the surface of the piezoelectric vibration element 20.

  Here, a manufacturing process of the piezoelectric vibration element 20 will be briefly described. The piezoelectric vibration element 20 is manufactured by, for example, forming a plurality of stacked bodies 21 together and then separating the connected stacked bodies 21 from each other. Then, the surface electrode layers 22 and 23 and the external electrodes 25 and 26 are formed on the separated individual laminates 21 to obtain the piezoelectric vibration element 20.

  In the piezoelectric vibration element 20 according to each of the above-described embodiments, burrs are generated on the surface in the separation step. Note that the step of separating the stacked body 21 may be performed before or after the stacked body 21 is fired. When separated before firing, burrs are likely to be formed so as to protrude from the upper and lower surfaces of the laminate 21, and when separated after firing, burrs are likely to be formed which project from the side surfaces of the laminate 21. And this burr | flash is utilized as protrusion 29a-29i mentioned above. Further, as described above, since the protrusions 29a to 29i are burrs generated in the production process of the piezoelectric vibration element 20, the protrusions 29a to 29i can be easily asymmetrical. However, the protrusions 29a to 29i are not necessarily burrs, and may be other shapes such as a resin as long as it protrudes from the surface of the piezoelectric vibration element 20.

  In the embodiment described above, the protrusions 29a and 29b are arranged on the upper and lower sides in FIG. 1A among the side surfaces 20a2 of the piezoelectric vibration element 20, but may be either one. Further, as shown in FIG. 10, the protrusions 29a and 29b may be provided on the left and / or right sides of the piezoelectric vibration element 20 in FIG. Furthermore, as shown in FIG. 11, protrusions 29a and 29b are formed by forming protrusions such as burrs on the side surfaces where the internal electrodes of the laminate 21 are exposed, and providing external electrodes 25 and 26 thereon. You may make it do. Note that the protrusions 29a and 29b may be arranged on all of the upper, lower, left and right sides in FIG. 1A of the side surface 20a2 of the piezoelectric vibration element 20, or as indicated by reference numeral 29 in FIG. It may be a single bowl-like shape that is continuous so as to surround the periphery. Here, the protrusions 29a and 29b have been described as examples, but the modification of the formation of the protrusions has been described.

  In the above-described embodiment, the piezoelectric vibration element 20 and the vibrating body 10 are covered with the covering layer 50. However, the present invention is not limited to this, and a configuration without the covering layer 50 may be used.

  Further, in the above-described embodiment, an example in which one piezoelectric vibration element 20 is disposed on the vibrating body 10 is illustrated, but two or more piezoelectric vibration elements 20 may be disposed. When there are two or more piezoelectric vibration elements 20, even if the piezoelectric vibration elements 20 are arranged on the same surface of the upper surface 10a of the vibrating body 10 (or the lower surface located on the opposite side of the upper surface 10a), the upper surface 10a and You may arrange | position on both surfaces of a lower surface. Further, although the piezoelectric vibration element 20 is rectangular in plan view, it may be square. Further, although the example in which the piezoelectric vibration element 20 is disposed at the approximate center of the vibration surface of the vibration body 10 is illustrated, the piezoelectric vibration element 20 may be disposed at a position deviated from the vibration surface center of the vibration body 10.

  Further, as the piezoelectric vibration element 20, a so-called bimorph type laminated type is illustrated, but a unimorph type piezoelectric vibration element can also be used.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

DESCRIPTION OF SYMBOLS 1 Sound generator 2 Sound generator 3 Electronic device 10 Vibrating body 20 Piezoelectric vibration element 29a-29i Protrusion 30 Frame body 40 Adhesive 50 Covering layer 200 Resonance box (housing)
300 Housing 301 Control circuit 302 Signal processing circuit 303 Radio circuit 304 Antenna

Claims (12)

A vibrating body,
A piezoelectric vibration element provided on the vibrating body,
The piezoelectric vibration element has a protrusion on at least a part of a surface thereof. The acoustic generator according to claim 1, wherein the protrusion has an asymmetric shape with respect to a center of the piezoelectric vibration element. The acoustic generator according to claim 1, wherein the piezoelectric vibration element includes a plurality of the protrusions. The acoustic generator according to claim 3, wherein the plurality of protrusions are disposed asymmetrically with respect to a center of the piezoelectric vibration element. The acoustic generator according to any one of claims 1 to 4, wherein the protrusion is disposed on a side surface adjacent to a surface of the piezoelectric vibration element facing the vibrating body. The sound generation according to claim 5, wherein the protrusion is disposed in the vicinity of a surface of the side surface facing the vibrating body and / or a surface on the opposite side of the facing surface. vessel. The sound generator according to claim 1, wherein the protrusion is disposed on a ridge line portion and / or a vertex portion of the piezoelectric vibration element. 8. The protrusion according to claim 1, wherein the protrusion disposed in the vicinity of the surface facing the vibrating body is embedded in an adhesive that bonds the piezoelectric vibration element to the vibrating body. The sound generator according to any one of the above. The sound generator according to any one of claims 1 to 8, wherein a tip of the protrusion has an acute angle. The acoustic generator according to any one of claims 1 to 9, wherein the piezoelectric vibration element is a bimorph laminated piezoelectric vibration element. The sound generator according to any one of claims 1 to 10,
A housing that houses the acoustic generator;
A sound generator comprising: The sound generator according to any one of claims 1 to 10,
An electronic circuit connected to the acoustic generator;
A housing for housing the electronic circuit and the acoustic generator;
Comprising at least
An electronic apparatus having a function of generating sound from the sound generator.

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