JP2014127974A - Acoustic generator, acoustic generation apparatus, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acoustic generator, an acoustic generation apparatus, and an electronic apparatus, having high durability with small variation in sound quality.SOLUTION: An acoustic generator 1 includes: a first frame body 10; a vibrator 20 provided on the first frame body 10 in a tense state; and an exciter 30 disposed on the vibrator 20. With the provision of a second frame body 50 on the circumference of the first frame body 10, it is possible to suppress a deformation of the first frame body 10 that receives large stress by the vibration of the vibrator 20, and reduce the overall deformation and deterioration of a complex vibrator constituted by the exciter 30, the vibrator 20, and the first frame body 10. Thus, the acoustic generator 1 of small sound quality variation, having the vibrator 20 with small deformation such as a warp if used for a long period is obtained.

Description

  The present invention relates to a sound generator, a sound generation device, and an electronic apparatus.

  Conventionally, an acoustic generator typified by a piezoelectric speaker has been known as a small-sized, low-current driving acoustic device using a piezoelectric body as an electroacoustic transducer, for example, a small electronic device such as a mobile computing device. It is used as an integrated sound generator.

  In general, an acoustic generator using a piezoelectric body as an electroacoustic transducer has a structure in which a piezoelectric vibrating element as an exciter in which an electrode made of a silver thin film or the like is formed on a metal vibrating plate is attached. The sound generation mechanism of an acoustic generator using a piezoelectric body as an electroacoustic transducer generates shape distortion in the piezoelectric vibration element by applying an alternating voltage to both sides of the piezoelectric vibration element, and the shape distortion of the piezoelectric vibration element is made of metal. The sound is generated by transmitting to the diaphragm and causing it to vibrate (see, for example, Patent Document 1).

  Further, an acoustic generator in which a resin film is used as a diaphragm instead of a metal diaphragm is known. In this acoustic generator, a bimorph-type laminated piezoelectric vibration element is sandwiched by a pair of resin films from the thickness direction, and the resin film is fixed to a frame member in a tensioned state. Thereby, acoustic conversion efficiency is improved and generation | occurrence | production of a high sound pressure is enabled (for example, refer patent document 2).

JP 2001-285994 A JP 2004-023436 A

  However, since the above-described conventional acoustic generator generates a high sound pressure by actively utilizing the resonance of the diaphragm, the peak (the portion where the sound pressure is higher than the surroundings) and the dip (in the frequency characteristics of the sound pressure) and the dip ( There is a problem that a portion having a sound pressure lower than that of the surroundings is likely to occur, and the load on the frame member to be fixed in a state where tension is applied to the vibrating body is large, so that the sound quality varies due to deformation or deterioration of the frame member. For this reason, the improvement of durability of a frame member is calculated | required.

  The present invention has been made in view of the above, and an object of the present invention is to provide an acoustic generator, an acoustic generator, and an electronic device that have high durability and little variation in sound quality.

  The acoustic generator of the present invention includes a first frame, a vibrating body stretched on the first frame, and an exciter provided on the vibrating body, and the first frame A second frame is further provided on the outer periphery of the body.

  A sound generator according to the present invention includes the above-described sound generator and a housing that houses the sound generator.

An electronic apparatus according to the present invention includes the above-described sound generator, an electronic circuit connected to the sound generator, and a housing that houses the electronic circuit and the sound generator, and outputs sound from the sound generator. It has the function to generate.

  According to the present invention, it is possible to provide an acoustic generator, an acoustic generator, and an electronic device that have high durability and little variation in sound quality.

It is explanatory drawing by the (a) top view of the acoustic generator which concerns on 1st Embodiment, and (b) A-A 'sectional view taken on the line of (a). It is sectional drawing which shows another example of 1st Embodiment. 1A is a block diagram of a sound generator, and FIG. 1B is a block diagram of an electronic device. It is explanatory drawing by the (a) top view of the acoustic generator which concerns on 2nd Embodiment, and B-B 'line sectional drawing of (b) (a). It is (a) typical perspective view for demonstrating each site | part of a frame, and (b) C-C 'sectional view taken on the line of (a). It is sectional drawing of the sound generator which concerns on 3rd Embodiment. It is sectional drawing which shows another example of 3rd Embodiment. It is explanatory drawing by the (a) top view of the acoustic generator which concerns on 4th Embodiment, (b) It is D-D 'sectional view taken on the line of (a). It is sectional drawing of the sound generator which concerns on 5th Embodiment.

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

(First embodiment)
The configuration of the sound generator according to the first embodiment will be described with reference to FIGS. 1 (a) and 1 (b).

  1A is an explanatory diagram in a 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 20, and FIG. It is AA 'line sectional drawing of 1 (a). For easy understanding, FIG. 1A and FIG. 1B illustrate a three-dimensional orthogonal coordinate system including the Z axis perpendicular to the main surface of the vibrating body 20. Such an orthogonal coordinate system may also be shown in other drawings used in the following description. Further, in FIG. 1B, the sound generator 1 is greatly exaggerated in the Z-axis direction for easy understanding.

  As shown in FIG. 1A, the sound generator 1 includes a first frame body 10, a vibration body 20, a piezoelectric vibration element 30, a second frame body 50, and lead wires (not shown). With.

  The vibrating body 20 can be formed using various materials such as resin, metal, and paper. For example, the thin plate-like vibrating body 20 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 vibration body 20 is made of a resin film, so that the vibration body 20 bends and vibrates with a large amplitude, thereby reducing the sound pressure. 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. Further, there is an advantage that the tension applied when the vibrating body 20 is fixed to the first frame 10 can be easily adjusted. A composite of metal and resin may be used as the vibrating body 20.

  The piezoelectric vibration element 30 includes a laminated body 33, surface electrode layers 34 and 35 formed on the upper and lower surfaces of the laminated body 33, and an external surface formed on the side surface where the end face of the internal electrode layer 32 of the laminated body 33 is exposed. Electrodes 36 and 37 are provided. Lead wires (not shown) are connected to the external electrodes 36 and 37. The main surface of the piezoelectric vibration element 30 is bonded to the main surface of the vibrating body 20 by an adhesive such as an epoxy resin.

  The laminated body 33 is formed by alternately laminating four piezoelectric layers 31a, 31b, 31c, 31d made of ceramics and three internal electrode layers 32. The piezoelectric vibration element 30 has a rectangular main surface on the upper surface side and the lower surface side, and the piezoelectric layers 31a and 31b and the piezoelectric layers 31c and 31d are polarized in different directions in the thickness direction, respectively. The piezoelectric layers 31b and 31c are polarized in the same direction.

  Therefore, when a voltage is applied to the piezoelectric vibration element 30 via the lead wire, for example, the lower surface side of the piezoelectric vibration element 30, in other words, the piezoelectric layers 31 c and 31 d on the vibration body 20 side contract, while the upper surface side piezoelectric element The body layers 31a and 31b are deformed so as to extend. Therefore, by applying an AC signal to the piezoelectric vibration element 30, the piezoelectric vibration element 30 can bend and vibrate, and the vibration body 20 can be bent. As described above, the piezoelectric layers 31a and 31b on the upper surface side of the piezoelectric vibration element 30 and the piezoelectric layers 31c and 31d on the lower surface side exhibit opposite expansion and contraction behavior, and as a result, the piezoelectric vibration element 30 is bent by a bimorph type. By vibrating, a certain vibration can be given to the vibrating body 20 to generate a sound.

  In this way, the piezoelectric vibration element 30 is a bimorph-type laminated piezoelectric vibration element, and the piezoelectric vibration element 30 itself bends and vibrates alone. Therefore, the piezoelectric vibration element 30 is, for example, a soft vibration body 20 regardless of the material of the vibration body 20. However, strong vibrations can be generated, and a sufficient sound pressure can be obtained with a small number of piezoelectric vibration elements 30.

  Here, as a material constituting the piezoelectric layers 31a, 31b, 31c, and 31d, a lead-free piezoelectric material such as lead zirconate titanate (PZT), a Bi layered compound, or a tungsten bronze structure compound has been conventionally used. The used piezoelectric ceramics can be used.

  The material of the internal electrode layer 32 is mainly composed of a metal such as silver and palladium. The internal electrode layer 32 may contain ceramic components constituting the piezoelectric layers 31a, 31b, 31c, and 31d, whereby the piezoelectric layers 31a, 31b, 31c, and 31d and the internal electrode layers 32 and 32 are included. , 32 can be obtained, and the piezoelectric vibration element 30 in which the stress due to the difference in thermal expansion is reduced.

  The surface electrode layers 34 and 35 and the external electrodes 36 and 37 are mainly composed of a metal such as silver. Moreover, you may contain a glass component. By containing the glass component, it is possible to obtain a strong adhesion between the piezoelectric layers 31a, 31b, 31c, 31d and the internal electrode layer 32 and the surface electrode layers 34, 35 or the external electrodes 36, 37. . The glass component content may be, for example, 20% by volume or less.

  The lead wire is an example of a wiring member. One end of the lead wire is connected to the piezoelectric vibration element 30, and an electric signal is input to the piezoelectric vibration element 30. Such lead wires can be formed using various metal materials. For example, if the lead wire is configured using flexible wiring in which a metal foil such as copper or aluminum is sandwiched between resin films, the acoustic generator 1 can be reduced in height.

The first frame 10 plays a role of holding the vibrating body 20 and forming a fixed end of vibration. For example, as shown in FIG. 1B, a first frame 10 is configured by joining a rectangular upper frame member 11 and a lower frame member 12 in the vertical direction. And the outer peripheral part of the vibrating body 20 which consists of a resin film is pinched | interposed between the upper frame member 11 and the lower frame member 12, and it fixes in the state which gave predetermined tension. Therefore, when the vibration body 20 vibrates greatly and generates a high sound pressure, a large stress is applied to the first frame body 10 that fixes the vibration body 20, and the first frame body 10 is deformed, There is a concern that the sound quality may fluctuate due to a change in tension applied to the vibrating body 20 due to deterioration of the joint.

  The second frame 50 is provided on the outer peripheral portion of the first frame 10 including the upper frame member 11 and the lower frame member 12 and supports the first frame 10. By supporting the first frame 10 by the second frame 50, deformation of the first frame 10 that receives a large stress due to vibration of the vibration body 20 is suppressed, and the piezoelectric vibration element 30, the vibration body 20, and the first vibration body 20 are suppressed. It is possible to reduce deformation and deterioration of the entire composite vibration body including one frame body 10. Therefore, the acoustic generator 1 includes the vibrating body 20 with little deformation such as deflection even when used for a long time.

  The thickness and material of the first frame body 10 and the second frame body 50 are not particularly limited, but in the first embodiment, for example, because of excellent mechanical strength and corrosion resistance, A stainless steel material having a thickness of 100 to 1000 μm is used.

  FIG. 1A shows the first frame 10 and the second frame 50 in which the shape of the inner region is a substantially rectangular shape, but a parallelogram, a trapezoid, and a regular n-gon. Such a polygon may be used. In the present embodiment, as shown in FIG.

  In the above description, the case where the first frame 10 is constituted by two frame members and the peripheral portion of the diaphragm 20 is sandwiched and supported by the two frame members is described as an example. It is not limited to. For example, as shown in FIG. 2, the first frame 10 may be constituted by a single frame member, and the peripheral portion of the diaphragm 20 may be bonded and supported to the first frame 10. . In FIG. 2, details of the laminated structure of the piezoelectric vibration element 30 are omitted, and a simplified rectangular shape is illustrated. Hereinafter, the description of the piezoelectric vibration element 30 in the cross-sectional views is similarly simplified.

  In addition, as shown in FIG. 1B, the acoustic generator 1 according to the first embodiment has a resin coating filled in the first frame 10 so as to embed the piezoelectric vibration element 30. Layer 40 is provided. Thus, by embedding the piezoelectric vibration element 30 with the resin coating layer 40, it is possible to induce an appropriate damping effect, suppress the resonance phenomenon, and further reduce the difference between the resonance peak and the dip. be able to. Further, the piezoelectric vibration element 30 can be protected from the external environment.

  In the first embodiment, the entire surface of the vibrating body 20 is covered with the coating layer 40, but it is not necessary to cover all of the surfaces. That is, the acoustic generator 1 only needs to cover the piezoelectric vibration element 30 and at least a part of the surface of the vibration body 20 on the side where the piezoelectric vibration element 30 is disposed with the coating layer 40.

  1B shows a state in which the resin layer 40, the first frame body 10, and the second frame body 50 are formed to have the same height in the Z-axis direction. The resin layer 40 only needs to have the piezoelectric vibration element 30 embedded therein. For example, the resin layer 40 may be formed to be higher than the height of the first frame body 10.

  In FIG. 1B, the bimorph laminated piezoelectric vibration element is exemplified as the piezoelectric vibration element 30. However, the piezoelectric vibration element 30 is not limited to this, and for example, the expanding and contracting piezoelectric vibration element 30 includes the vibrating body 20. It may be a unimorph type pasted on.

  Next, a sound generator equipped with the sound generator 1 according to the first embodiment will be described with reference to FIG. FIG. 3A is a block diagram of the sound generator.

  As shown in FIG. 3A, the sound generator 4 can be configured by housing the sound generator 1 having the above-described configuration in a resonance box 400. The resonance box 400 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 4 can be used alone as a speaker, and can be suitably incorporated into various electronic devices 2, for example.

  As described above, the difference between the resonance peak and the dip in the frequency characteristic of the sound pressure, which was disadvantageous in the piezoelectric speaker, can be reduced, and the durability is high, and the variation in sound quality is small. The sound generator 1 according to the embodiment can be suitably incorporated into an electronic device 2 such as a mobile phone, a thin television, or a tablet terminal.

  Note that the electronic device 2 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, and for example, a refrigerator, a microwave oven, a vacuum cleaner, a washing machine, and the like. Conventionally, home appliances that have not been focused on sound quality are also included.

  Here, the electronic device 2 including the above-described sound generator 1 will be briefly described with reference to FIG. FIG. 3B is a block diagram of the electronic device 2. The electronic device 2 includes the acoustic generator 1 described above, an electronic circuit connected to the acoustic generator 1, and a housing 200 that houses the acoustic generator 1 and the electronic circuit.

  Specifically, as illustrated in FIG. 3B, the electronic device 2 includes an acoustic generator 1, an electronic circuit including a control circuit 21, a signal processing circuit 22, and a wireless circuit 23 as an input device, and an antenna 24. And a housing 200 for storing them. Although a wireless input device is shown in FIG. 3B, 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, a speaker) with which the electronic device 2 is provided. In addition, in FIG. 3B, one acoustic generator 1 is illustrated, but two or more acoustic generators 1 and other oscillators may be provided.

  The control circuit 21 controls the entire electronic device 2 including the wireless circuit 23 via the signal processing circuit 22. An output signal to the sound generator 1 is input from the signal processing circuit 22. Then, the control circuit 21 generates a sound signal S by controlling the signal processing circuit 22 from the signal input to the radio circuit 23 and outputs the sound signal S to the sound generator 1.

  In this way, the electronic device 2 shown in FIG. 3B incorporates the small and thin acoustic generator 1 while reducing the difference between the resonance peak and the dip and suppressing the frequency fluctuation as much as possible. In addition, it is possible to improve the sound quality as a whole in a low sound region and a high sound region, and to reduce fluctuations in sound quality.

  In addition, in FIG.3 (b), although the electronic device 2 which directly mounted the sound generator 1 was illustrated as a sound output device, as a sound output device, the sound generator which accommodated the sound generator 1 in the housing | casing, for example 4 may be installed.

(Second Embodiment)
The configuration of the acoustic generator according to the second embodiment will be described with reference to FIGS. 4 (a) and 4 (b).

  Here, from the viewpoint of making the following explanation easy to understand, FIG. 5A and FIG. 5B are used for the names of the respective parts of the first frame 10 and the second frame 50 in the present embodiment. I will tell you. FIG. 5A is a schematic perspective view for explaining each part of the first frame 10, and FIG. 5B is a cross-sectional view taken along the line CC ′ of FIG. is there. In FIG. 5A, only one of the two frame members constituting the frame 10 is shown.

  As shown in FIG. 5A, in the present embodiment, among the end surfaces of the first frame body 10, an end surface along the XY plane is expressed as an “edge surface”. Similarly, among the end faces of the first frame 10, the end face along the Z-axis is referred to as a “side face”, and the “side faces” located inside the first frame are collectively referred to as an “inner peripheral face”, the first The “side surfaces” located outside the frame body 10 are generally expressed as “outer peripheral surfaces”. 5B, the distance between the inner peripheral surface and the outer peripheral surface in the cross section parallel to the XY plane is “the width of the edge surface” w, and the thickness of the first frame 10 in the Z-axis direction. Is expressed as t. The “edge surface” and the “side surface” in the present invention may be parallel to the XY plane and the Z axis, respectively, or may form an angle smaller than 45 °. The “edge surface” and “side surface” may be a flat surface or a curved surface.

  Further, as shown in FIG. 5B, in the present embodiment, a portion of the “side surface” that is close to the “edge surface” is expressed as an “end portion” of the first frame body in the Z-axis direction.

  Further, as shown in FIG. 5A, in the present embodiment, the inner area of the first frame 10 is “inside the frame” of the first frame, and the outer area is “outside of the frame”. Express each one. These names are also expressed in the same manner in the second frame 50.

  In the second embodiment, the width w2 of the edge surface of the second frame body 50 in the direction parallel to the main surface of the vibrating body 20, that is, the XY direction, is the edge surface of the first frame body 10 adjacent thereto. It is assumed that it is larger than the width w1. By making w2 larger than w1, the deformation of the first frame body 10 is further suppressed, and the deformation and deterioration of the entire composite vibration body composed of the piezoelectric vibration element 30, the vibration body 20 and the first frame body 10 are prevented. Further reduction can be achieved.

(Third embodiment)
FIG. 6 is a cross-sectional view showing the configuration of the sound generator according to the third embodiment in the YZ cross section. In the third embodiment, the edge surface of the first frame body 10 is closer to the vibrating body 20 than the edge surface of the second frame body 50, that is, the Z-axis positive side. It shall protrude in the direction of.

  As described above, the first frame body 10 is a support body that supports the vibrating body 20 while applying uniform tension. However, the first frame body 10 itself can also be regarded as a component of the composite vibrating body. When vibrating, the first frame body 10 itself is also vibrated by the resonance of the vibrating body 20 and returns a reflected wave to the vibrating body 20.

Since the edge surface of the first frame body 10 projects beyond the edge surface of the second frame body 50, the first frame body 10 holds the vibrating body 20 and forms a fixed end of vibration. The second frame 50 has a region supported by the second frame 50 and a region that does not have a role of holding the vibrating body 20 and is not supported by the second frame 50. That is, since the symmetry of the first frame 10 in the Z-axis direction is reduced, the resonance frequency of the first frame 10 is dispersed, and the reflected wave returning from the first frame 10 to the vibrating body 20 is disturbed. Is done. As a result, the piezoelectric vibration element 30, the vibration body 20, and the first
The difference between the resonance peak and the dip in the frequency characteristics of the sound pressure of the entire composite vibrator comprising the frame 10 is reduced, and the sound quality is improved by suppressing the frequency fluctuation of the sound pressure as much as possible. it can.

  In FIG. 6, the edge surface of the first frame 10 protrudes in the positive direction of the Z axis from the edge surface of the second frame 50, and the second frame 50 is in the negative direction of the Z axis. However, the thickness t2 of the second frame 50 is made smaller than the thickness t1 of the first frame 10. The edge surface of the second frame 50 and the edge surface of the first frame 10 may be arranged at the same height in the negative direction of the Z-axis, as shown in FIG. You may arrange | position so that the edge surface of the 1st frame 10 may protrude in both the positive / negative direction of a Z-axis rather than the edge surface of the 2nd frame 50. FIG.

(Fourth embodiment)
A configuration of an acoustic generator according to the fourth embodiment will be described with reference to FIGS. 8A and 8B. In the fourth embodiment, an intervening layer 60 is provided between the outer peripheral surface of the first frame 10 and the inner peripheral surface of the second frame 50 that face each other. The intervening layer 60 is, for example, an adhesive, and is a member having a Young's modulus lower than that of the first frame body 10 and the second frame body 50. Thus, in the fourth embodiment, the first frame 10 and the second frame 50 have the intervening layer 60 having a Young's modulus lower than that of the first frame 10 and the second frame 50. Fixed through.

  The first frame 10 oscillates the first frame 10 itself as one of the components of the composite vibration body and returns a reflected wave to the vibration body 20, but the outer periphery of the first frame 10. The second frame 50 that is provided in the section and supports the first frame 10 is also guided by the vibration of the first frame 10 and the second frame 50 itself vibrates and the first frame 50 itself is also vibrated. A reflected wave is returned to the frame 10 and can be regarded as one of the components of the composite vibrator.

  Since a material having a low Young's modulus usually has a small mechanical Q value, that is, a large mechanical loss, by providing such an intervening layer 60, the vibration of the first frame 10 is absorbed by the intervening layer 60, The vibration transmitted to the second frame 50 can be attenuated. In addition, the reflected wave returned from the second frame 50 to the first frame 10 can be similarly attenuated, and the influence of the second frame 50 on the sound quality of the composite vibrator can be minimized. Can do.

  Therefore, in the fourth embodiment, it is possible to reduce the deformation and deterioration of the first frame body 10 and further the entire composite vibration body to obtain a highly durable acoustic generator 1, and the acoustic generator 1. It is possible to minimize the influence of the second frame 50 on the sound quality.

  The intervening layer 60 may have a void. In the case of having a void, vibration energy is further absorbed by the void, and mutual vibrations are hardly transmitted between the first frame 10 and the second frame 50. The influence of the second frame 50 can be further reduced.

(Fifth embodiment)
FIG. 9 is a cross-sectional view showing the configuration of the sound generator according to the fifth embodiment in the YZ cross section. In the fifth embodiment, an intervening layer 60 is provided between the outer peripheral surface of the first frame body 10 and the inner peripheral surface of the second frame body 50 that face each other, and the first frame body 10. A gap 70 in which no intervening layer 60 exists is provided between the end portion of the outer peripheral surface in the Z-axis direction and the end portion of the inner peripheral surface of the second frame 50 in the Z-axis direction. As described above, the gap 70 is provided at least at a part between the outer peripheral surface of the first frame 10 and the inner peripheral surface of the second frame 50, so that the first frame 10 and the second frame are provided. The energy of vibration by the body 50 is absorbed and attenuated by the gap 70, and mutual vibration is hardly transmitted between the first frame body 10 and the second frame body 50.

  In the fifth embodiment, the case where the intervening layer 60 is provided between the outer peripheral surface of the first frame 10 and the inner peripheral surface of the second frame 50 is illustrated, but the intervening layer 60 is provided. Similarly, the first frame 10 and the second frame 50 are provided by providing a gap 70 between the outer peripheral surface of the first frame 10 and the inner peripheral surface of the second frame 50 even in the case where there is not. Damping effect of vibration between the two is obtained. In this case, since the vibration damping effect due to the intervening layer 60 does not exist, the vibration damping effect due to the gap 70 becomes more prominent.

  Further, in the fifth embodiment, the portion where the gap 70 is provided is the end of the outer peripheral surface of the first frame 10 in the Z-axis direction and the end of the inner peripheral surface of the second frame 50 in the Z-axis direction. However, the present invention is not limited to this. When the gap 70 is provided on either the positive side or the negative side of the end portion in the Z-axis direction, the gap 70 is further set to the first level. The above-described effect can be obtained even when the frame 10 is provided at least at a part between the outer peripheral surface of the frame 10 and the inner peripheral surface of the second frame 50.

  In addition, between the outer peripheral surface of the first frame 10 and the inner peripheral surface of the second frame 50, a gap 70 is provided on either the positive side or the negative side of the end in the Z-axis direction. In this case, the symmetry of the first frame 10 in the Z-axis direction is reduced, the resonance frequency of the first frame 10 is dispersed, and a reflected wave returning from the first frame 10 to the vibrating body 20 is generated. It is disturbed, and the effect that the difference between the resonance peak and the dip in the frequency characteristic of the sound pressure of the entire composite vibrator is reduced is also obtained.

  In the above-described embodiment, the case in which the vibrating body is configured by a thin film such as a resin film has been described as an example. However, the embodiment is not limited thereto, and may be configured by, for example, a plate-shaped member.

  Further, in the acoustic generator described above, an example in which one piezoelectric vibration element is disposed on the vibration body is illustrated, but two or more piezoelectric vibration elements may be disposed on the vibration body.

  Further, in each of the above-described embodiments, the case where a piezoelectric vibration element is used as an example of an exciter has been described as an example. However, the exciter is not limited to a piezoelectric vibration element, and an electric signal is input. What has a function to vibrate is sufficient. For example, an electrodynamic exciter, an electrostatic exciter, or an electromagnetic exciter well known as an exciter for vibrating a speaker may be used. The electrodynamic exciter is such that an electric current is passed through a coil disposed between the magnetic poles of a permanent magnet to vibrate the coil. A bias and an electric signal are passed through the plate to vibrate the metal plate, and an electromagnetic exciter is an electric signal that is passed through the coil to vibrate a thin iron plate.

  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 Electronic device 4 Sound generator 10 1st frame 20 Vibrating body 30 Piezoelectric vibration element 40 Covering layer 50 2nd frame 60 Intervening layer 70 Gap

Claims (10)

A first frame, a vibrating body stretched on the first frame, and an exciter provided on the vibrating body,
A sound generator further comprising a second frame body on an outer peripheral portion of the first frame body. In a direction parallel to the main surface of the vibrator,
2. The sound generator according to claim 1, wherein a width of an edge surface of the second frame is larger than a width of an edge surface of the first frame. On the side of the vibrator on which the exciter is provided,
The sound generator according to claim 1, wherein at least a part of the edge surface of the first frame body protrudes from the edge surface of the second frame body. The thickness of the second frame body in the direction perpendicular to the main surface of the vibrating body is:
4. The sound generator according to claim 1, wherein a thickness of the first frame body is smaller than a thickness in a direction perpendicular to the main surface of the vibrating body. Having an intervening layer between the outer peripheral surface of the first frame and the inner peripheral surface of the second frame facing each other;
The sound generator according to any one of claims 1 to 4, wherein the intervening layer has a Young's modulus lower than that of the first frame and the second frame.   6. A gap is provided in at least a part between an outer peripheral surface of the first frame body and an inner peripheral surface of the second frame body facing each other. Sound generator.   At least one of the end portions in the direction perpendicular to the main surface of the vibrating body of at least one of the outer peripheral surface of the first frame and the inner peripheral surface of the second frame. The sound generator according to claim 6, wherein the sound generator is provided on one side.   The sound generator according to any one of claims 1 to 7, wherein the exciter is a bimorph laminated piezoelectric vibration element.   An acoustic generator comprising: the acoustic generator according to any one of claims 1 to 8; and a housing that houses the acoustic generator.   An acoustic generator according to any one of claims 1 to 8, an electronic circuit connected to the acoustic generator, and a housing that accommodates the electronic circuit and the acoustic generator, from the acoustic generator An electronic device having a function of generating sound.

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