WO2015145795A1

WO2015145795A1 - Acoustic generator, acoustic generation device, and electronic apparatus

Info

Publication number: WO2015145795A1
Application number: PCT/JP2014/069834
Authority: WO
Inventors: 拓郎牧迫
Original assignee: 京セラ株式会社
Priority date: 2014-03-27
Filing date: 2014-07-28
Publication date: 2015-10-01
Also published as: JP6174786B2; JPWO2015145795A1

Abstract

[Problem] To provide an acoustic generator, which has excellent sound qualities, and is not susceptible to being affected due to vibration from the outside, an acoustic generation device, and an electronic apparatus. [Solution] An acoustic generator (1) of the present invention includes: a piezoelectric element (11) as an exciter; a diaphragm (12), which has the piezoelectric element (11) attached thereto, and which vibrates by means of vibration of the piezoelectric element (11); a frame body (13) that supports the diaphragm (12); and a bonding material (15) that is provided between the diaphragm (12) and the frame body (13). Voids (151) are provided in the bonding material (15).

Description

SOUND GENERATOR, SOUND GENERATOR, AND ELECTRONIC DEVICE

The present invention relates to an acoustic generator, an acoustic generator, and an electronic device using a piezoelectric element.

Conventionally, an acoustic generator using a piezoelectric element is known (see, for example, Patent Document 1). Such an acoustic generator is configured to vibrate a diaphragm by applying a voltage to a piezoelectric element attached to the diaphragm to vibrate, and to output sound by actively utilizing resonance of the vibration. For example, such a sound generator is housed in a housing and used as a sound generator, and is used by being incorporated in a small electronic device such as a mobile computing device.

WO2012 / 001954

In the above-described sound generator, sound generator, and electronic device, further improvement in sound quality is required. Furthermore, there is also a demand for improvement in that sound quality deteriorates due to the influence of external vibration.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an acoustic generator, an acoustic generator, and an electronic device that have good sound quality and are not easily affected by external vibration.

An acoustic generator according to the present invention includes an exciter, a diaphragm to which the exciter is attached, and which vibrates due to vibration of the exciter, a frame that supports the diaphragm, the diaphragm, and the frame And a void in the bonding material.

Also, a sound generator according to the present invention is characterized by comprising the above-described sound generator and a housing for housing the sound generator.

According to another aspect of the invention, there is provided an electronic device including the above-described acoustic generator, an electronic circuit connected to the acoustic generator, and a housing that houses the electronic circuit and the acoustic generator. It has the function to generate | occur | produce.

According to the acoustic generator of the present invention, by providing voids in the bonding material, the strength of the bonding material can vary, the resonance is divided, damped, and the sound pressure curve is flattened. Accordingly, since the peak dip is reduced, the sound quality is improved. Furthermore, since vibrations from the outside such as the casing are absorbed, deterioration in sound quality due to external vibrations can be reduced.

Further, according to the sound generator and the electronic device of the present invention, since the sound generator with improved sound quality is used, a high sound quality sound generator and electronic device can be realized.

(A) is a schematic plan view showing an example of an embodiment of the sound generator of the present invention, (b) is a schematic cross-sectional view taken along line AA shown in (a), and (c) is an example of a main part X. FIG. (A) is a schematic plan view showing another example of the embodiment of the sound generator of the present invention, (b) is a schematic cross-sectional view along the line AA shown in (a), and (c) is a main part X. It is an expanded sectional view showing an example. It is an expanded sectional view which shows the other example of the principal part X of the acoustic generator of this invention. It is an expanded sectional view which shows the other example of the principal part X of the acoustic generator of this invention. It is an expanded sectional view which shows the other example of the principal part X of the acoustic generator of this invention. (A) is a schematic plan view which shows the other example of embodiment of the sound generator of this invention, (b) is an expanded sectional view which shows an example of the principal part X of the sound generator shown to (a). is there. It is an expanded sectional view which shows the other example of the principal part X of the acoustic generator of this invention. It is a graph which shows an example of the frequency characteristic of the acoustic generator of a comparative example. It is a graph which shows an example of the frequency characteristic of the acoustic generator of this invention. It is a figure which shows the structure of embodiment of the sound generator of this invention. It is a figure which shows the structure of one Embodiment of the electronic device of this invention.

Hereinafter, an example of an embodiment of a sound generator of the present invention will be described with reference to the drawings.

FIG. 1 (a) is a schematic plan view showing an example of an embodiment of the sound generator of the present invention, FIG. 1 (b) is a schematic sectional view taken along line AA shown in FIG. 1 (a), and FIG. c) is an enlarged sectional view showing an example of the main part X; FIG. 2 (a) is a schematic plan view showing another example of the embodiment of the sound generator of the present invention, and FIG. 2 (b) is a schematic cross-sectional view along the line AA shown in FIG. 2 (a). FIG. 2C is an enlarged cross-sectional view showing an example of the main part X.

The acoustic generator 1 in the example shown in FIG. 1 is provided with a piezoelectric element 11 as an exciter, a diaphragm 12 that vibrates with the piezoelectric element 11 due to vibration of the piezoelectric element 11, and a diaphragm 12 Including a frame body 13 that supports the outer peripheral portion of the diaphragm 12 and a bonding material 15 interposed between the outer peripheral portion of the diaphragm 12 and the frame body 13, and a void 151 is included in the bonding material 15.

For example, a piezoelectric element 11 is used as an exciter constituting the acoustic generator 1. A configuration in which the piezoelectric element 11 is used as an exciter includes a laminate in which a piezoelectric layer and an internal electrode layer are laminated to form a plate, and a surface electrode layer and an internal electrode layer provided on the surface. A form provided with an external electrode or the like provided on the side surface from which is derived is preferably used.

The piezoelectric element 11 is attached to the surface of the diaphragm 12, for example, and is excited by exciting the diaphragm 12 by applying a voltage. In the case where the piezoelectric element 11 is used as an exciter, the piezoelectric element 11 includes, for example, a laminate in which four piezoelectric layers made of ceramics and three internal electrode layers are alternately laminated, A surface electrode layer formed on the upper surface and the lower surface; and an external electrode formed on a side surface from which the internal electrode layer is derived.

The piezoelectric layer constituting the piezoelectric element 11 is formed of ceramics having piezoelectric characteristics, and as such ceramics, lead zirconate titanate, lithium niobate, lithium tantalate, Bi layered compound Conventionally used piezoelectric ceramics such as lead-free piezoelectric materials such as tungsten bronze structure compounds can be used. The thickness of one layer of the piezoelectric layer is preferably set to 0.01 to 0.1 mm, for example, so as to be driven at a low voltage. In order to obtain a large bending vibration, it is preferable to have a piezoelectric constant d31 of 200 pm / V or more.

Further, the internal electrode layer constituting the piezoelectric element 11 is formed by simultaneous firing with the ceramic forming the piezoelectric layer, and includes a first internal electrode layer and a second internal electrode layer. Piezoelectric layers which are alternately stacked with the piezoelectric layers and sandwich the piezoelectric layers from above and below, and the first internal electrode layer and the second internal electrode layer are arranged in the stacking order, so that they are sandwiched between them A drive voltage is applied to the layer. As a material for forming the internal electrode layer, various metal materials can be used. For example, a conductor mainly composed of silver or silver-palladium whose reactivity with piezoelectric ceramics is low, or a conductor containing copper, platinum or the like can be used, and these may contain a ceramic component or a glass component. . When the internal electrode layer is made of a material containing a metal component composed of silver and palladium and a ceramic component that constitutes the piezoelectric layer, the stress due to the thermal expansion difference between the piezoelectric layer and the internal electrode layer is reduced. Therefore, it is possible to obtain the piezoelectric element 11 having no stacking failure.

As the exciter, for example, the piezoelectric element 11 made of a plate-like body in which the main surfaces on the upper surface side and the lower surface side have a polygonal shape such as a rectangular shape or a square shape, or a circular shape or an elliptical shape is preferable. By using the piezoelectric element 11 and the diaphragm 12 and the frame 13 described later, the acoustic generator 1 can be made thin.

Furthermore, it is preferable that the piezoelectric element 11 has a bimorph structure. That is, it is preferable that the direction of polarization with respect to the direction of the electric field applied at a certain moment is polarized so as to be reversed between one side and the other side in the thickness direction. Since it contributes to the reduction in thickness and can vibrate the diaphragm efficiently with less energy, a high-volume sound generator can be obtained.

The diaphragm 12 constituting the acoustic generator 1 can be formed using various materials such as resin and metal. For example, the diaphragm 12 can be made of a resin film such as polyethylene, polyimide, acrylic resin having a thickness of 0.4 mm to 1.5 mm.

The piezoelectric element 11 as an exciter is attached to the diaphragm 12. Specifically, the main surface of the piezoelectric element 11 is joined to the main surface of the diaphragm 12 with an adhesive such as an epoxy resin.

Then, the vibration of the exciter (piezoelectric element 11) causes the diaphragm 12 to vibrate together with the exciter (piezoelectric element 11). For example, when the piezoelectric element 11 is a piezoelectric element having a bimorph structure, when a lead wire is connected to the external electrode and an electric signal is input to the piezoelectric element via this lead wire (when a voltage is applied), At a certain moment, the piezoelectric layer on the side bonded to the diaphragm 12 (the lower surface side of the piezoelectric element 11) contracts in the in-plane direction perpendicular to the stacking direction, and the piezoelectric layer on the upper surface side of the piezoelectric element 11 extends in the stacking direction. It is deformed so as to extend in the vertical in-plane direction, and is bent toward the diaphragm 12 side. Therefore, by applying an AC signal to the piezoelectric element 11, the piezoelectric element 11 can bend and vibrate, and the diaphragm 12 can be bent. Note that a flexible substrate (FPC) can be used instead of the lead wire, which is advantageous for thinning.

And the frame 13 is provided so that the outer peripheral part of the diaphragm 12 may be supported. As the frame 13, for example, a frame member whose inner peripheral shape and outer peripheral shape are rectangular can be used. In the example shown in FIG. 1, the frame 13 is composed of a single frame member, and the sound generating unit 10 is configured by attaching the outer peripheral portion of the diaphragm 12 to the frame member 13. On the other hand, in the example illustrated in FIG. 2, the frame body 13 includes two

frame members

131 and 132, and supports the diaphragm 123 by sandwiching the outer peripheral portion of the diaphragm 12. The outer peripheral portion of the diaphragm 12 is sandwiched and fixed between two

frame members

131 and 132 constituting the frame body 13. In this way, the diaphragm 12 is supported by the frame body 13 while being stretched within the frame of the frame body 13. A portion of the diaphragm 12 in FIG. 1 located inside the frame 13 and a portion of the diaphragm 12 in FIG. 2 that is not sandwiched between the two

frame members

131 and 132 constituting the frame 13 are shown in FIG. It can be freely vibrated.

The thickness and material of the two

frame members

131 and 132 constituting the frame body 13 are not particularly limited. The frame 13 can be formed using various materials such as metal, resin, and glass. For example, a stainless steel member having a thickness of 0.1 to 5.0 mm can be suitably used as the frame member 13 and the

frame members

131 and 132 constituting the frame member 13 because of excellent mechanical strength and corrosion resistance. . The width of the frame member 13 and the

frame members

131 and 132 constituting the frame member 13 is, for example, 1.2 to 10.0 mm. 1 and 2 show the frame 13 whose inner region has a substantially rectangular shape, it may be a polygon such as a parallelogram, a trapezoid, or a regular n-gon, or a circular shape. Or oval.

The acoustic generator 1 further includes a resin layer 14 provided so as to cover the surfaces of the piezoelectric element 11 and the diaphragm 12 within the frame of the frame body 13 and vibrates together with the piezoelectric element 11 and the diaphragm 12. Good.

The resin layer 14 is preferably formed using, for example, an acrylic resin so that the Young's modulus is in the range of 1 MPa to 1 GPa, for example. The resin layer 14 is not necessarily provided until the surface of the piezoelectric element 11 is covered, but is provided until the surface of the piezoelectric element 11 is covered (the piezoelectric element 11 is embedded in the resin layer 14). Since a moderate damping effect can be induced, the resonance phenomenon can be suppressed and the peak or dip in the frequency characteristic of the sound pressure can be suppressed to a small value. In the drawing, the resin layer 14 is formed so as to have the same height as the frame body 13, but the resin layer 14 may be formed to be higher than the height of the frame body 13.

Here, the diaphragm 12, the frame 13, the bonding material 15, and the resin layer 14 can be integrated and can be regarded as a composite vibrator that vibrates as a whole.

In addition, although the figure illustrates the case where there is one exciter (piezoelectric element 11), the number of exciters (piezoelectric element 11) is not limited. Moreover, although the figure shows the case where the piezoelectric element 11 is provided on one main surface of the diaphragm 12, the piezoelectric element 11 may be provided on both surfaces of the diaphragm 12. In addition, as the piezoelectric element 11, a bimorph type stacked piezoelectric element has been described as an example, but a unimorph type piezoelectric element may be used.

The acoustic generator 1 according to the present embodiment includes a bonding material 15 interposed between the outer peripheral portion of the diaphragm 12 and the frame body 13, and the bonding material 15 includes a void 151.

According to this configuration, the strength of the bonding material 15 can vary, and the resonance of the composite vibrating body in which the diaphragm 12, the frame 13, the bonding material 15, and the resin layer 14 are integrated is divided, damped, and sound pressure. The curve is flattened. Accordingly, since the peak dip is reduced, the sound quality is improved. Furthermore, since vibrations from outside such as the housing and the frame 13 are absorbed, it is possible to reduce deterioration in sound quality due to external vibrations.

As shown in FIG. 2, when the frame 13 is composed of two

frame members

131 and 132, it is interposed between the outer periphery of the diaphragm 12 and the frame member 131 on the side where the piezoelectric element 11 is disposed. It is preferable that the bonded material 15 has a void 151 and the bonding material 15 interposed between the outer peripheral portion of the diaphragm 12 and the frame member 132 on which the piezoelectric element 11 is not disposed has the void 151. However, the structure which has the void 151 only in any one bonding material 15 may be sufficient.

As the bonding material 15, for example, an adhesive such as a UV curable resin, a thermosetting resin (acrylic), an anaerobic UV curable resin, or a UV thermosetting resin is used. Specifically, acrylic resins, epoxy resins, silicone resins, polyester resins and the like are used. For example, using an acrylic adhesive for the bonding material 15 is soft and can contribute to peak dip suppression. The thickness of the bonding material 15 is, for example, 10 to 80 μm.

As a method for joining the diaphragm 12 to the frame 13 in the case where an adhesive made of UV curable resin is used as the joining material 15, an excimer treatment is performed on the front and back of the diaphragm 12 in a tensioned state, and then vibration A UV curable resin is applied to the upper surface of the plate 12 in the shape of the frame 13 (frame member 131) using a method such as printing or a dispenser. Then, a primer is applied to the frame 13 (frame member 131) and dried, and then the frame 13 (frame member 131) is slowly placed on the UV curable resin. After that, it is pressed from above and further irradiated with UV to be cured. When the frame body 13 (frame member 132) is joined under the diaphragm 12, UV curable resin is printed on the lower surface of the diaphragm 12 in the shape of the frame body 13 (frame member 132) using a method such as printing or a dispenser. Application may be made and the same method as described above may be used. Further, when an adhesive made of a thermosetting resin is used as the bonding material 15, it may be heated instead of the above UV irradiation when cured. The same applies to UV thermosetting.

Various methods can be used as a method of forming the void 151 in the bonding material 15 for bonding the diaphragm 12 and the frame 13. For example, when stirring with a stirrer, the void 151 can be produced in the bonding material 15 by stirring so as to entrap air. Alternatively, a method may be used in which the bonding material 15 is cured after the void 151 is formed by applying the bonding material 15 before curing and injecting gas into a desired location of the bonding material 15. For example, the void 151 is formed by injecting a gas through the tube while the tip of the thin tube is applied to the boundary between the bonding material 15 and the frame 13 or the diaphragm 12 and the tip of the tube is moved along the boundary. By subsequently curing the bonding material 15, a void 151 can be provided at the boundary with the frame 13 or the diaphragm 12. Alternatively, a method of applying the uncured bonding material 15 to the surface of the frame 13 after placing the hollow resin spheres at a desired location may be used. Alternatively, the void 151 may be moved by vacuum defoaming and positioned on the outer peripheral side of the bonding material 15. Moreover, you may mix a hollow resin ball | bowl with the joining material 15 before hardening. Further, by partially applying the bonding material 15, the void 151 can penetrate the bonding material 15 from the boundary with the diaphragm 12 to the boundary with the frame body 13.

Here, as shown in FIG. 3, it is preferable that the void 151 faces the boundary between the diaphragm 12 and the bonding material 15 or the boundary between the frame 13 and the bonding material 15. The presence of the void 151 facing these boundaries makes it easier for the bonding material 15 to follow the vibration change, and further makes it difficult for the bonding material 15 to transmit vibration from the outside to the diaphragm 12, so that the sound quality is improved. . In addition, the void 151 facing the boundary between the diaphragm 12 and the bonding material 15 or the boundary between the frame body 13 and the bonding material 15 is not a perfect sphere, and the boundary between the diaphragm 12 and the frame body 13 is not It is preferable that the shape expands in a direction in contact with the boundary (a direction parallel to the boundary). Thereby, since the area of the void 151 facing the boundary with the diaphragm 12 or the boundary with the frame body 13 can be increased, the above-described effect can be improved.

The boundary between the diaphragm 12 and the bonding material 15 refers to the surface where the diaphragm 12 and the bonding material 15 are in contact, and the boundary between the frame body 13 and the bonding material 15 refers to the frame body 13 and the bonding material 15. Refers to the surface that is touching.

Further, as shown in FIG. 4, it is preferable that the void 151 penetrates the bonding material 15 from the boundary between the diaphragm 12 and the bonding material 15 to the boundary between the frame 13 and the bonding material 15. By providing the void 151 penetrating between the frame 13 and the diaphragm 12, vibration passing through the void 151 without using the bonding material 15 is also generated, so that the arrival time of vibration is shifted and vibration due to external vibration is generated. This has the effect of reducing the size and further improves the sound quality.

Further, as shown in FIG. 5, it is preferable that the void 151 is located at the outer peripheral end of the bonding material 15. Here, the end portion on the outer peripheral side of the bonding material 15 is the end portion of the bonding material 15 on the side corresponding to the outer periphery of the diaphragm 12, and the distance from the outer wall surface of the bonding material 15 is 20 of the entire width. The area in the range up to%. By providing the void 151 at the end portion on the outer peripheral side of the bonding material 15 in this manner, durability can be improved because it is easy to follow deformation due to external pressure.

As shown in FIGS. 1 and 2, the void 151 may not be in contact with the diaphragm 12 and the frame body 13, and it is possible to prevent cracks from developing in the bonding material 15 due to vibration, and vibration It is possible to prevent the plate 12 from peeling off and to prevent the vibration plate 12 from lowering the tension.

When the void 151 included in the bonding material 15 is, for example, spherical, the diameter of each void 151 is, for example, 10 to 120 μm, and the length is, for example, 50 to 150% of the thickness (0.01 mm to 0.08 mm) of the bonding material 15. Is set. In the case where the void 151 has an irregular shape, for example, the projected area circle equivalent diameter (the diameter of a circle having the same area as the projected area of the void 151) is set to 10 to 120 μm.

The voids 151 included in the bonding material 15 are preferably scattered in the entire circumferential direction in a plan view, and at this time, the voids 151 may be unevenly present in the circumferential direction. The voids 151 included in the bonding material 15 are biased in the circumferential direction, i.e., the proportion of the voids 151 in the bonding material 15 is different in the circumferential direction to divide the resonance, making the resonance frequencies difficult to align, An effect of suppressing peak dip can be obtained. The proportion of the voids 151 in the bonding material 15 is set such that, for example, the area ratio of the voids 151 as viewed in a cross section is in a range of 0.1 to 25%.

Further, as shown in FIG. 6, the bonding material 15 has a protruding portion 150 that protrudes from the inner edge of the frame body 13, and when the entire inner edge of the frame body 13 is viewed, the protruding amount of the protruding portion 150 is not large. It may be uniform. For example, the protruding portion 150 protrudes with the same thickness over the entire circumference, and the protruding distance of the protruding portion 150 (the distance from the inner edge of the frame body 13) has different portions when viewed over the entire periphery. Thus, in the region inside the inner edge of the frame 13, the region that vibrates with the diaphragm 12 alone and the region that vibrates with the structure in which the diaphragm 12 and the bonding material 15 are joined are mixed, and the respective resonance conditions are different. Therefore, it becomes difficult for the resonance frequencies to be aligned, and the peak dip can be further suppressed, and the sound quality can be improved.

When the entire inner edge of the frame 13 is viewed, the amount of protrusion is non-uniform. When the entire inner edge of the frame 13 is viewed, the amount of protrusion is different from the other parts at least in one place. It means that there is a portion 150, and it is not limited to the presence of a protruding portion 150 having a protruding amount different from other portions on each side of the inner edge of the frame 13.

Further, examples in which the amount of protrusion is not uniform include a form in which the thickness of the protruding part 150 protruding at the same distance is different, and a form in which both the protruding distance and thickness of the protruding part 150 are different.

Note that the protruding width (the protruding distance) of the protruding portion 150 is, for example, 0.5 mm to 2.0 mm, preferably 0.1 mm to 1.0 mm in the cross section of FIG. 6B.

Furthermore, as shown in FIG. 7, it is preferable that the protruding portion 150 that protrudes from the inner edge of the frame 13 is also provided with a void 151, which not only changes the resonance condition, but also how the vibration is transmitted by the void 151. By changing, it becomes more difficult to align the resonance frequencies, and the peak dip can be further suppressed.

Here, the difference in sound quality (frequency characteristic of sound pressure) between the case where a bonding material not containing voids (FIG. 8) and the case where a bonding material containing voids (FIG. 9) is used will be described.

8 and 9 are graphs showing an example of frequency characteristics of sound pressure. FIG. 8 shows the frequency characteristics of sound pressure when no void is included in the bonding material. FIG. 9 shows the frequency characteristics of the sound pressure in the case where the boundary of the bonding material 15 and all the voids that are connected and penetrate the bonding material 15 in the bonding material 15 are included. In the graphs shown in FIGS. 8 and 9, the horizontal axis indicates the frequency, and the vertical axis indicates the sound pressure. The sound generator in which the frequency characteristic of the sound pressure shown in FIGS. 8 and 9 is measured has the same configuration except for the presence or absence of voids, that is, each member, its size and material.

The peaks and dips located in the frequency band of 700 Hz to 1.4 kHz in FIG. 8 and the frequency bands of 700 Hz to 1.5 kHz shown in FIG. 9 and the frequency bands of 4 kHz to 8 kHz shown in FIG. Comparing the peak and dip, it can be seen that the peak and dip in the graph shown in FIG. 8 are clearly smaller.

As described above, when the void 151 is included in the bonding material 15, the peak and dip are reduced in most frequency bands and the flatness of the sound pressure is improved compared to the case where no void is included. The frequency characteristics of pressure are improved.

Next, an example of an embodiment of the sound generator of the present invention will be described.

The sound generator 20 is a sound generation device such as a so-called speaker, and includes, for example, a sound generator 1 and a housing 30 that houses the sound generator 1 as shown in FIG. The housing 30 resonates the sound generated by the sound generator 1 and radiates the sound to the outside through an opening (not shown) formed in the housing 30. The housing 30 can be formed using various materials such as metals such as aluminum and magnesium alloys, and resins such as polycarbonate. By having such a housing 30, for example, the sound pressure in a low frequency band can be increased.

Such a sound generator 20 can be used alone as a speaker, and can be suitably incorporated into a portable terminal, a thin-screen TV, a tablet terminal, or the like, as will be described later. Moreover, it can also be incorporated into home appliances that have not been prioritized in terms of sound quality, such as refrigerators, microwave ovens, vacuum cleaners, and washing machines.

According to the sound generator 20 of the present example, since the sound generator 1 is improved in sound quality, a high sound quality sound generator can be obtained.

Next, an electronic device equipped with an acoustic generator will be described with reference to FIG. FIG. 11 is a diagram illustrating a configuration of the electronic device 50 according to the embodiment. In the figure, only components necessary for explanation are shown, and descriptions of general components are omitted.

As shown in FIG. 11, the electronic device 50 of this example includes an acoustic generator 1, an electronic circuit 60 connected to the acoustic generator 1, and a housing 40 that houses the electronic circuit 60 and the acoustic generator 1. And having a function of generating sound from the sound generator 1. In the example illustrated in FIG. 11, the electronic device 50 is a mobile terminal device such as a mobile phone or a tablet terminal.

As shown in FIG. 11, the electronic device 50 includes an electronic circuit 60. The electronic circuit 60 includes, for example, a controller 50a, a transmission / reception unit 50b, a key input unit 50c, and a microphone input unit 50d. The electronic circuit 60 is connected to the sound generator 1 and has a function of outputting an audio signal to the sound generator 1. The sound generator 1 generates sound based on the sound signal input from the electronic circuit 60.

Moreover, the electronic device 50 includes a display unit 50e, an antenna 50f, and the sound generator 1, and includes a housing 40 that accommodates these devices. Although FIG. 11 shows a state in which each device including the controller 50a is accommodated in one housing 40, the accommodation form of each device is not limited. In the present embodiment, it is sufficient that at least the electronic circuit 60 and the sound generator 1 are accommodated in one housing 40.

The controller 50 a is a control unit of the electronic device 50. The transmission / reception unit 50b transmits / receives data via the antenna 50f based on the control of the controller 50a. The key input unit 50c is an input device of the electronic device 50 and accepts a key input operation by an operator. The microphone input unit 50d is also an input device of the electronic device 50, and accepts a voice input operation by an operator. The display unit 50e is a display output device of the electronic device 50, and outputs display information based on the control of the controller 50a.

The sound generator 1 operates as a sound output device in the electronic device 50. The sound generator 1 is connected to the controller 50a of the electronic circuit 60, and emits sound upon application of a voltage controlled by the controller 50a.

In FIG. 11, the electronic device 50 has been described as a portable terminal device. However, the electronic device 50 is not limited to the type of the electronic device 50, and may be applied to various consumer devices having a function of emitting sound. . For example, flat-screen televisions and car audio devices can of course be used for products having a function of generating sound, for example, various products such as vacuum cleaners, washing machines, refrigerators, microwave ovens, and the like.

According to the electronic device 50 of this example, since it is configured using the sound generator 1 with improved sound quality, a high sound quality electronic device can be obtained.

Next, a mobile terminal equipped with an acoustic generator will be described.

As shown in FIG. 11, the portable terminal of this example includes an acoustic generator 1, an electronic circuit 60 connected to the acoustic generator 1, a housing 40 that houses the electronic circuit 60 and the acoustic generator 1, and a display And has a function of generating sound from the sound generator 1.

That is, in the above-described electronic device 50, the portable terminal of this example has a configuration including a display which is a display device having a function of displaying image information as the display unit 50e shown in FIG. For example, known displays such as a liquid crystal display and an organic EL display can be suitably used. The display may have an input device such as a touch panel.

Here, the joining member for joining the acoustic generator 1 to the housing 40 is a joining member including at least a part of a viscoelastic body. The joining member may be a single member made of only a viscoelastic body or a composite body made up of several members including a viscoelastic body. As such a joining member, for example, a double-sided tape in which an adhesive is attached to both surfaces of a base material layer made of a nonwoven fabric or the like can be suitably used. The thickness of the joining member is set to 0.1 mm to 0.6 mm, for example.

Examples of the electronic circuit 60 include a circuit for processing image information to be displayed on a display and audio information transmitted by a portable terminal, a communication circuit, and the like. At least one of these circuits may be included, or all the circuits may be included. Further, it may be a circuit having other functions. Furthermore, you may have a some electronic circuit. The electronic circuit and the sound generator are connected by connection wiring.

A part of the housing 40 may be a display, or a part of the housing 40 may be a display cover and a display may be disposed inside the display 40.

Note that the mobile terminal has a communication means (communication unit) that transmits and receives data via an antenna or the like. For example, mobile phones such as smartphones, mobile devices such as tablet PCs and notebook PCs, game machines, and the like can be given.

Since such a portable terminal is configured using the sound generator 1 with improved sound quality, a high-quality portable terminal can be realized.

DESCRIPTION OF SYMBOLS 1 Sound generator 11 Piezoelectric element 12 Diaphragm 13

Frame body

131, 132 Frame member 14 Resin layer 15 Bonding material 151 Void 20 Sound generator 30, 40 Case 50 Electronic device 50a Controller 50b Transmission / reception part 50c Key input part 50d Microphone input Part 50e display part 50f antenna 60 electronic circuit

Claims

An exciter, a vibration plate that is attached to the exciter, vibrates due to vibration of the exciter, a frame that supports the vibration plate, and a joint that is interposed between the vibration plate and the frame. A sound generator comprising a material and a void in the bonding material.
2. The acoustic generator according to claim 1, wherein the void faces a boundary between the diaphragm and the bonding material or a boundary between the frame body and the bonding material.
3. The sound generator according to claim 2, wherein the void penetrates the bonding material from a boundary between the diaphragm and the bonding material to a boundary between the frame body and the bonding material.
The sound generator according to any one of claims 1 to 3, wherein the void is located at an outer peripheral end of the bonding material.
The sound generator according to claim 1, wherein the void is not in contact with the diaphragm and the frame.
The bonding material has a protruding portion protruding from the inner edge of the frame, and the protruding amount of the protruding portion is non-uniform when the entire inner edge of the frame is viewed. The sound generator according to any one of claims 1 to 5.
The sound generator according to claim 6, wherein the void is also present in the protruding portion.
The sound generator according to any one of claims 1 to 7, wherein the bonding material is an acrylic adhesive.
A sound generator comprising: the sound generator according to any one of claims 1 to 8; and a housing that houses the sound 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 houses the electronic circuit and the acoustic generator, An electronic device having a function of generating sound from a sound generator.