JP6567911B2 - SOUND GENERATOR, SOUND GENERATOR HAVING THE SAME, AND ELECTRONIC DEVICE - Google Patents

Description

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

  2. Description of the Related Art Conventionally, there has been a piezoelectric speaker composed of a diaphragm, a frame member that supports the outer periphery of the diaphragm, a piezoelectric element provided on the diaphragm in the frame of the frame member, and a resin layer that covers the piezoelectric element. It is known (see, for example, Patent Document 1).

  Also known is a piezoelectric speaker that supports the outer peripheral portion of the diaphragm so as to be sandwiched between a pair of frame members (see, for example, Patent Document 2).

Japanese Utility Model Publication No.57-128299 Japanese Utility Model Publication 2-90600

  In recent years, improvement in sound pressure of piezoelectric speakers has been demanded, and there are cases where sound pressure is improved by high voltage driving. However, in the piezoelectric speaker as described above, when it is continuously driven at a high voltage, although the sound pressure can be improved initially, there is a risk that the diaphragm will loosen with the lapse of the driving time and the sound pressure will decrease. .

  The present invention has been made in view of the above circumstances, and is capable of suppressing a decrease in sound pressure even when continuously driven at a high voltage, and has a highly reliable sound generator, a sound generator including the sound generator, and an electronic device. The purpose is to provide.

An acoustic generator according to the present invention includes a diaphragm, a frame member that supports an outer peripheral portion of the diaphragm, and an exciter provided on the diaphragm in the frame of the frame member. At least a part of the outer peripheral portion protrudes from the frame member toward the outside of the frame, and an adhesive is provided from the protruding diaphragm to the outer surface of the frame member, and the adhesive is bonded to the outer surface of the frame member. wherein the relief there Rukoto in the height direction of the surface.

  According to another aspect of the present invention, there is provided an acoustic generator including the acoustic generator having the above-described configuration and a housing that accommodates the acoustic generator.

  According to another aspect of the invention, there is provided an electronic apparatus including the acoustic generator having the above-described configuration, an electronic circuit connected to the acoustic generator, and a housing that houses the electronic circuit and the acoustic generator.

  According to the sound generator of this embodiment, even when continuously driven at a high voltage, a decrease in sound pressure can be suppressed, and a sound generator having excellent reliability can be realized. Moreover, according to the sound generator and the electronic device of the present embodiment, it is possible to realize a sound generator and an electronic device having excellent sound performance with high sound pressure, high sound quality, and high reliability.

(A) is a schematic plan view which shows an example of the acoustic generator of this embodiment, (b) is the schematic sectional drawing cut | disconnected by the AA line shown to (a). (A) is a schematic plan view which shows the other example of the acoustic generator of this embodiment, (b) is the schematic sectional drawing cut | disconnected by the AA line shown to (a). (A) is a schematic plan view which shows the other example of the acoustic generator of this embodiment, (b) is the schematic front view seen from the direction of the arrow shown to (a). It is a schematic sectional drawing which shows the other example of the acoustic generator of this embodiment. It is a schematic sectional drawing which shows the other example of the acoustic generator of this embodiment. It is a block diagram which shows an example of the sound generator of this embodiment. It is a block diagram which shows an example of the electronic device of this embodiment. (A) is a graph which shows an example of the frequency-sound pressure characteristic of the sound generator of this embodiment, (b) is a graph which shows the frequency-sound pressure characteristic of the conventional sound generator used as a comparative example.

  Hereinafter, an example of the sound generator of the present embodiment will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

  FIG. 1A is a schematic plan view showing an example of the sound generator of the present embodiment, and FIG. 1B is a schematic cross-sectional view taken along the line AA shown in FIG. The acoustic generator 1 shown in FIG. 1 includes a diaphragm 12, a frame member 13 that supports the outer periphery of the diaphragm 12, and a piezoelectric element as an exciter provided on the diaphragm 12 in the frame of the frame member 13. 11, at least a part of the outer peripheral portion of the diaphragm 12 protrudes from the frame member 13 toward the outside of the frame, and an adhesive 15 is provided from the protruding diaphragm 12 to the outer surface of the frame member 13.

  The piezoelectric element 11 constituting the acoustic generator 1 is not shown in its configuration, but includes, for example, a laminated body in which a piezoelectric layer and an internal electrode layer are laminated to form a plate, and this laminated body It is possible to adopt a form including an external electrode provided on the side surface from which the internal electrode layer is derived and a surface electrode connected to the external electrode and provided on the main surface of the laminate. The piezoelectric element 11 is provided on the main surface of the vibration plate 12 positioned within the frame of the frame member 13. The piezoelectric element 11 vibrates the vibration plate 12 by receiving a voltage and vibrating.

The piezoelectric layer constituting the piezoelectric element 11 is formed of ceramics having piezoelectric characteristics. As such ceramics, lead zirconate titanate is used.
Conventionally used piezoelectric ceramics such as lead-free piezoelectric materials such as lithium niobate, lithium tantalate, Bi layered compounds, and tungsten bronze structure compounds can be used. The thickness of the piezoelectric layer is set to 0.04 to 1.0 mm, for example. In order to obtain a large bending vibration, it is preferable to have a piezoelectric constant d31 of 200 pm / V or more.

  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. The piezoelectric layers are alternately stacked to sandwich the piezoelectric layer from above and below. As a material for forming the internal electrode layer, various metal materials can be used. For example, a conductor containing silver or silver-palladium as a main component that can be fired at a low temperature, or a conductor containing copper, platinum, or the like can be used. However, a ceramic component or a glass component may be contained therein. 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.

  Moreover, as a material of the external electrode and the surface electrode constituting the piezoelectric element 11, a silver compound containing nickel or glass containing silica as a main component, nickel, or the like can be used.

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

  The piezoelectric element 11 may have, for example, a monomorph structure (single layer piezoelectric body) having one piezoelectric layer, but preferably has a bimorph structure with two or more piezoelectric layers. Thereby, while contributing to thickness reduction, the diaphragm 12 can be vibrated efficiently with little energy. Further, in a bimorph structure in which the direction of displacement due to an electric field applied at a certain moment is reversed between the one side and the other side in the thickness direction, the piezoelectric element 11 itself undergoes flexural vibration, whereby the diaphragm 12 can reduce the mechanical loss at the joint surface, which can contribute to the improvement of the sound pressure.

  The electrical connection between the surface electrode and the internal electrode layer may be made by a through conductor penetrating the piezoelectric layer, instead of the external electrode as described above.

  The diaphragm 12 constituting the acoustic generator 1 can be formed using various materials such as resin and metal. For example, a diaphragm 12 having a thickness of 10 to 200 μm made of a metal plate such as stainless steel, or a resin film such as polyethylene, polyimide, acrylic, polycarbonate, or polybutylene terephthalate can be used.

  A 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.

  The diaphragm 12 is vibrated by the vibration of the piezoelectric element 11. For example, a wiring member (not shown) is connected to the surface electrode of the piezoelectric element 11, and an electric signal is input to the piezoelectric element 11 through this wiring member. Here, when the piezoelectric element 11 extends in the in-plane direction (a direction parallel to the main surface of the diaphragm 12), the diaphragm 12 is bent so as to be convex toward the piezoelectric element 11. Next, when the positive and negative electrodes of the electrical signal are reversed in this state, the piezoelectric element 11 contracts, and the diaphragm 12 is bent so as to be concave toward the piezoelectric element 11 side. That is, by applying an AC signal to the piezoelectric element 11, the piezoelectric element 11 can be expanded and contracted, and bending vibration can be applied to the diaphragm 12.

  A frame member 13 is provided so as to support the outer peripheral portion of the main surface of the diaphragm 12. Here, the frame member 13 has a main surface (lower surface in FIG. 1) of the frame member 13 and an outer peripheral portion of the main surface (upper surface in FIG. 1) of the diaphragm 12 such as a thermosetting resin or a UV thermosetting resin. The outer peripheral part of the main surface of the diaphragm 12 is supported by being bonded via an adhesive.

  As the frame member 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 member 13 is provided only on the one main surface side of the diaphragm 12. However, as shown in FIG. 5 described later, the frame member 13 is also provided on the other main surface side of the diaphragm 12. The outer peripheral portion of the diaphragm 12 may be sandwiched and supported by the first frame member 131 on the one main surface side and the second frame member 132 on the other main surface side.

  As the thickness (height) of the frame member 13 (the first frame member 131 and the second frame member 132), for example, a thickness of 100 μm to 5.0 mm can be employed.

Moreover, as a material of the frame member 13, various materials, such as glass, a metal, and resin, can be used, for example. When the frame member 13 is made of glass or metal, the rigidity is high, so the deformation is small and the sound quality is stable. On the other hand, when the frame member 13 is made of resin, the rigidity is smaller than that of glass or metal, and deformation due to vibration of the diaphragm 12 is likely to occur, and therefore spurious vibration is easily induced in the resonance of the diaphragm 12. Therefore, resonance peaks are dispersed in the sound pressure characteristics, and the peaks and dip can be reduced, and the frequency characteristics can be flattened. Therefore, the sound quality can be improved by flattening the sound pressure.

  Further, the frame member 13 may be assembled by arranging a plurality of members in the circumferential direction, and these may be joined to each other.

  In addition, FIG. 1 shows an example in which the outer peripheral shape of the frame member 13 is a rectangular shape, and the inner peripheral shape is also a rectangular shape, but in this way the aspect ratio is larger than 1, This contributes to dispersion of resonance and can contribute to reduction of peaks and dip. However, it may be a polygon such as a square, a parallelogram, a trapezoid, and a regular n-gon, or a circle or an ellipse.

  Further, as shown in FIG. 1, a resin layer 14 may be provided so as to cover the piezoelectric element 11 in the frame of the frame member 13 as necessary.

  Although FIG. 1 illustrates the case where there is one piezoelectric element 11, the number of piezoelectric elements 11 is not limited. 1 shows an example in which the piezoelectric element 11 is provided on one main surface of the diaphragm 12, but the piezoelectric elements 11 may be provided on both main surfaces of the diaphragm 12, respectively.

  In the acoustic generator of the present embodiment, at least a part of the diaphragm 12 protrudes from the frame member 13 toward the outside of the frame. In the acoustic generator 1 shown in FIG. Both end portions along the side protrude from the frame member 13 toward the outside of the frame. The term “outside the frame” as used herein means the outside of the outer periphery of the frame member 13 when viewed from the direction perpendicular to the main surface of the diaphragm 12. Also means that there is a part of the diaphragm 12 outside.

  Further, an adhesive 15 is provided from the protruding diaphragm 12 to the outer surface of the frame member 13. In other words, the adhesive 15 is raised and provided on the main surface of the diaphragm 12 protruding outside the frame of the frame member 13, and the adhesive 15 adheres to the outer surface of the frame member 13, and the main surface of the diaphragm 12. The top and the outer surface of the frame member 13 are joined.

  Here, as the adhesive 15, for example, an adhesive such as a thermosetting resin or a UV thermosetting resin can be employed. The main surface (the lower surface in FIG. 1) of the frame member 13 and the one main surface of the diaphragm 12 ( The same adhesive as that interposed between the outer peripheral portion of the upper surface in FIG. 1 may be used, or a different adhesive may be used.

  By adopting such a configuration, the adhesive strength between the diaphragm 12 and the frame member 13 is increased, and the diaphragm 12 does not loosen even when continuously driven at a high driving voltage, so that a decrease in sound pressure level can be suppressed. The acoustic generator 1 with improved reliability can be obtained.

  In addition, the maximum protrusion amount (maximum protrusion distance) of the diaphragm 12 protruding outside the frame from the frame member 13 when viewed in plan is set to, for example, 50 μm to 2.0 mm. And the maximum distance (maximum protrusion distance of the adhesive agent 15) from the outer periphery of the frame member 13 at the time of planar view to the front-end | tip of the adhesive agent 15 is set, for example to 50 micrometers-1.0 mm, and when it sees from a horizontal direction The maximum distance from the main surface of the diaphragm 12 to the tip of the adhesive 15 (maximum height of the adhesive 15) is set to, for example, 80 μm to 1.0 mm.

  Here, as shown in FIG. 2, the diaphragm 12 protrudes from the frame member 13 toward the outside of the frame over the entire circumference, and the adhesive 15 is provided from the protruding diaphragm 12 to the outer surface of the frame member 13. More preferred. By adopting such a configuration, the adhesive strength with the frame member 13 is further increased, and the diaphragm 12 is not loosened even if the drive voltage is increased and continuously driven, so that a decrease in sound pressure level can be further suppressed.

  As shown in FIG. 3, the adhesive 15 is more preferably undulated in the height direction of the adhesive surface on the outer surface of the frame member 13. By adopting such a configuration, since the stress against the peeling of the adhesive 15 from the outer surface of the frame member 13 is dispersed, a decrease in the bonding strength between the diaphragm 12 and the frame member 13 can be further suppressed, and the sound pressure level Can be further suppressed.

  Here, the difference in height between the peak of the adjacent mountain and the bottom of the valley on the outer surface of the frame member 13 is set to, for example, 10 to 30 μm, and the maximum height (the height of the highest peak of the mountain) and the minimum height. The difference from (the bottom height of the lowest valley) is set to 10 to 20 μm, for example.

  Although not shown, the outer peripheral shape of the adhesive surface on the main surface of the diaphragm 12 when viewed in plan may be a shape having irregularities.

  As shown in FIG. 4, the adhesive 15 may be adhered to the outer surfaces of the diaphragm 12 and the frame member 13 in a meniscus shape. With such a configuration, since the reflected wave of the vibration propagated to the frame member 13 is dispersed, the distortion caused by the reflected wave can be reduced and the sound quality can be improved. In addition to the meniscus shape, the surface may be a curved surface, the surface may be inclined with respect to the vertical direction, or the like.

  Here, as shown in FIG. 5, the frame member 13 includes a first frame member 131 and a second frame member 132, and the outer surface of the first frame member 131 extends from one main surface of the protruding diaphragm 12. And a second adhesive 152 is provided from the other main surface of the projecting diaphragm 12 to the outer surface of the second frame member 132, and the first adhesive 151 is provided. More preferably, the height of the adhesive surface on the outer surface of the first frame member 131 of the agent 151 is different from the height of the adhesive surface on the outer surface of the second frame member 132 of the second adhesive 152.

  With such a configuration, it is possible to superimpose spurious vibrations having different resonance frequencies on the vibration caused by the reflected wave of the vibration propagated to the frame member 13, the reflected wave vibration is divided, and the peak / dip in the frequency characteristic is obtained. Therefore, sound quality can be improved.

  In addition, when the height of the adhesive surface on the outer surface of the first frame member 131 of the first adhesive 151 is, for example, 50 to 100 μm, the adhesive surface on the outer surface of the second frame member 132 of the second adhesive 152. The difference from the height is set to 50 to 100 μm, for example.

  Next, the manufacturing method of the sound generator of this embodiment is demonstrated.

First, a ceramic green sheet to be a piezoelectric layer constituting the piezoelectric element is produced. Specifically, a ceramic slurry is prepared by mixing a calcined powder of piezoelectric ceramic, a binder made of an organic polymer such as acrylic or butyral, and a plasticizer. And a ceramic green sheet is produced using this ceramic slurry by using tape molding methods, such as a doctor blade method and a calender roll method. As the piezoelectric ceramic, any material having piezoelectric characteristics may be used. For example, a perovskite oxide made of lead zirconate titanate (PbZrO ₃ —PbTiO ₃ ) can be used. As the plasticizer, dibutyl phthalate (DBP), dioctyl phthalate (DOP), or the like can be used.

  In addition, you may produce a ceramic molded object using other manufacturing methods, such as press molding and extrusion molding.

  Further, when a laminated body including a piezoelectric layer and an internal electrode layer is manufactured, a conductive paste to be an internal electrode layer is manufactured. Specifically, a conductive paste is prepared by adding and mixing a binder and a plasticizer to a silver-palladium metal powder. This conductive paste is applied to the above ceramic green sheet in a desired internal electrode layer pattern using a screen printing method, and a plurality of ceramic green sheets printed with this conductive paste are laminated to form a ceramic green sheet. A laminated body may be used.

  The ceramic green sheet or ceramic green sheet laminate obtained above is subjected to a binder removal treatment at a predetermined temperature, then fired at a temperature of 900 ° C. to 1200 ° C., and a predetermined shape using a surface grinder or the like. By subjecting to a grinding process, a single-layer piezoelectric body or a multilayer body including alternately laminated internal electrode layers and piezoelectric body layers is produced.

  Note that any manufacturing method may be used as long as a single-layer piezoelectric body or a multilayer body in which a plurality of internal electrode layers and piezoelectric body layers are stacked can be manufactured.

  Next, a silver glass-containing conductive paste prepared by adding a binder, a plasticizer, and a solvent to a mixture of conductive particles mainly composed of silver and glass, and the main surface of the piezoelectric body or the laminate and After printing on the side surface with a predetermined pattern by a screen printing method or the like and drying, a baking process is performed at a temperature of 600 ° C. to 800 ° C. to form a surface electrode and an external electrode.

  Thereafter, the piezoelectric body or the laminate is subjected to polarization treatment to impart piezoelectric activity. For the polarization treatment, for example, the first surface electrode provided on the surface of the piezoelectric element is connected to the negative electrode and the second surface electrode is connected to the positive electrode, for example, 2 kV / mm to 3 kV / mm. The potential difference may be applied for several seconds as the application time at an ambient temperature of 15 ° C. to 35 ° C. The voltage, ambient temperature, and application time are suitably selected depending on the properties of the piezoelectric material.

  The desired piezoelectric element 11 can be obtained as described above. However, when a wiring member is necessary, it may be connected to the piezoelectric element 11 by the following method. For example, when a flexible wiring board is connected and fixed (bonded) to the piezoelectric element 11 using a conductive adhesive, a conductive adhesive paste is applied and formed at a predetermined position of the piezoelectric element 11 using a technique such as screen printing. To do. Then, the flexible wiring board is connected and fixed to the piezoelectric element 11 by curing the conductive adhesive paste with the flexible wiring board being in contact therewith. The conductive adhesive paste may be applied and formed on the flexible wiring board side.

  In addition, as the wiring member, an insulation-coated lead wire may be used, and solder may be used as the joining member, and a member having the same function can be suitably selected.

  Next, the diaphragm 12 is produced. For example, when the diaphragm 12 is made of a metal such as stainless steel, the diaphragm 12 is made in a desired shape by press punching or etching. Further, when the diaphragm 12 is made of a resin such as an acrylic resin, a polycarbonate resin, or a polybutylene terephthalate resin, it is made by injection molding using a mold that is made to have a desired shape. Moreover, when producing the diaphragm 12 with resin films, such as polyethylene and a polyimide, it produces by the press punching process or laser cut with a desired shape.

Next, the piezoelectric element 11 is bonded and fixed to one main surface of the diaphragm 12 using a bonding material. For example, when an anaerobic resin adhesive is used as the bonding material, an anaerobic adhesive paste is applied and formed at a predetermined position on the one main surface side of the diaphragm 12 using a technique such as screen printing.

  Thereafter, pressure is applied in a state where the piezoelectric element 11 is in contact, and the anaerobic adhesive paste is cured, whereby the piezoelectric element 11 is bonded and fixed to the diaphragm 12. The anaerobic adhesive paste may be applied and formed on the piezoelectric element 11 side.

  Next, the frame member 13 is produced. For example, when the frame member 13 is made of a metal such as stainless steel, it is made by press punching or etching. Further, when the frame member 13 is made of a resin material such as an acrylic resin, a polycarbonate resin, or a polybutylene terephthalate resin, it is made by injection molding using a mold.

  Next, the diaphragm 12 is bonded and fixed to the main surface of the frame member 13 processed by the above method using an adhesive 15. For example, when an anaerobic resin adhesive is used as the adhesive 15, anaerobic adhesive paste is applied and formed at a predetermined position on the main surface side of the diaphragm 12 using a technique such as screen printing, and then the frame 15 The frame member 13 is bonded and fixed to the diaphragm 12 by applying pressure in a state where the member 13 is in contact to cure the anaerobic adhesive paste. The anaerobic adhesive paste may be applied and formed on the frame member 13 side. As the other adhesive 15, for example, an adhesive such as a thermosetting epoxy adhesive can be used.

  Here, in order to have a configuration in which at least a part of the outer peripheral portion of the diaphragm 12 protrudes from the frame member 13 toward the outside of the frame, the diaphragm 12 may be cut larger than the frame member 13 by a laser. Moreover, what is necessary is just to apply and adjust the application quantity and application position of an adhesive agent, in order to set it as the structure by which the adhesive agent 15 is provided from the protruding diaphragm 12 to the outer surface of the frame member 13. FIG.

  The configuration in which the outer peripheral portion of the diaphragm 12 protrudes from the frame member 13 toward the outside of the frame over the entire circumference and the adhesive is provided from the protruding diaphragm 12 to the outer surface of the frame member 13 is the same as described above. It is obtained by the method.

  Moreover, in order to make the structure with undulations in the height direction of the adhesive surface on the outer surface of the frame member 13, the coating amount may be adjusted as appropriate by a dispenser or printing, and the adhesive 15 forms the diaphragm 12 and the frame member in meniscus shape. The coating direction and the coating amount may be adjusted as appropriate even in a configuration in which the coating is bonded to the outer surface of 13.

  The frame member 13 includes a first frame member 131 and a second frame member 132, and the first adhesive 151 extends from one main surface of the protruding diaphragm 12 to the outer surface of the first frame member 131. The second adhesive 152 is provided from the other main surface of the protruding diaphragm 12 to the outer surface of the second frame member 132, and the first frame member 131 of the first adhesive 151 is provided. In order to obtain a configuration in which the height of the adhesive surface on the outer surface of the second adhesive 152 is different from the height of the adhesive surface on the outer surface of the second frame member 132 of the second adhesive 152, the coating amount and the coating time may be adjusted as appropriate. .

  In the above description, the vibration plate 12 processed into a desired shape is prepared and the piezoelectric element 11 is bonded, and then the vibration plate 11 and the frame member 13 are bonded. In particular, a resin film is used as the vibration plate 12. In the case of using the resin film, the plurality of piezoelectric elements 11 and the plurality of frame members 13 may be bonded to a large-area resin film, and then the resin film may be laser-cut so as to have a desired shape.

  The sound generator of this embodiment is obtained by the above manufacturing method.

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

  The sound generation device is a sound generation device such as a so-called speaker. As shown in FIG. 6, the sound generation device 20 of this example includes a sound generator 1 and a housing 30 that houses the sound generator 1. Note that a part of the housing 30 may be the diaphragm 12 constituting the acoustic generator 1, and that the housing 30 accommodates the acoustic generator 1 means that a part of the acoustic generator 1 (piezoelectric element 11). ) Is also included.

  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. 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 television, 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.

  Since the sound generator 20 of the present embodiment described above is configured using a sound generator that can suppress a decrease in sound pressure even when continuously driven at a high voltage and has improved reliability, it has a high sound pressure and high sound quality. Therefore, the acoustic performance with high reliability is obtained.

  Next, an example of the electronic apparatus of this embodiment will be described.

  As shown in FIG. 7, 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 has a function of generating sound from the sound generator 1.

  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.

  In addition, 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. 7 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. 7, the electronic device 50 is 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.

  The above-described electronic device of the present invention is configured using a highly reliable sound generator that can suppress a decrease in sound pressure even when continuously driven at a high voltage, and thus has high sound pressure, high sound quality, and high reliability. Therefore, it has excellent acoustic performance.

  Next, a specific example of the sound generator of this embodiment will be described.

  A bimorph-structured piezoelectric element in which 8 piezoelectric layers of lead zirconate titanate and 7 internal electrode layers of silver are laminated has a length of 65 mm, a width of 35 mm, and a thickness of 2 mm. It was plate-shaped. Further, the diaphragm was made of a resin film having a thickness of 25 μm, and the diaphragm was produced so as to protrude from the frame member to the outside of the frame, and the sound generator of the example was prepared.

  The frame member is composed of a pair of upper and lower frame members made of stainless steel, and the outer peripheral portion of the diaphragm is sandwiched between the pair of frame members. Each frame member has an inner circumference of 30 mm in length and 60 mm in width, an outer circumference of 35 mm in length and 65 mm in width, a width of 2.5 mm in plan view, and a thickness (height) of 1.0 mm. It was.

  Moreover, the diaphragm protruded from the frame member to the outside of the frame over the entire circumference, and the protruding distance was 1 mm.

  Furthermore, the adhesive is made of an epoxy-based adhesive, and the adhesive between the frame member and the diaphragm protrudes outside the frame member over the entire circumference, and there are undulations in the height direction of the adhesive surface on the outer surface of the frame member. The form (form of FIG. 3) was used. Here, the maximum protruding distance of the adhesive from the outer periphery of the frame member in plan view was 100 μm, and the maximum height of the adhesive as viewed from the direction perpendicular to the outer surface of the frame member was 100 μm.

  The sound pressure level characteristic, which is the acoustic characteristic of the example produced as described above, was measured. The result is shown in FIG.

  On the other hand, as a comparative example, an acoustic generator having the same configuration as the acoustic generator of the example was manufactured except that the diaphragm did not protrude from the frame member to the outside of the frame and the adhesive was not provided outside the frame. . Also for this sound generator, the sound pressure level characteristic, which is an acoustic characteristic, was measured in the same manner as in the above example. The result is shown in FIG.

  Comparing FIG. 8A and FIG. 8B, it can be seen that the sound pressure level characteristics of the sound generator of the example are clearly improved compared to the sound generator of the comparative example.

  From the above, at least a part of the outer peripheral portion of the diaphragm protrudes from the frame member toward the outside of the frame, and an adhesive is provided from the protruding diaphragm to the outer surface of the frame member. It was confirmed that the level characteristics could be improved.

DESCRIPTION OF SYMBOLS 1 Sound generator 11 Piezoelectric element 12 Diaphragm 13 Frame member 131 1st frame member 132 2nd frame member 14 Resin layer 15 Adhesive 151 1st adhesive 152 2nd adhesive 20 Sound generator 30,40 Enclosure 50 Electronic device 60 Electronic circuit

Claims (6)

A diaphragm, a frame member that supports the outer periphery of the diaphragm, and an exciter provided on the diaphragm in the frame of the frame member, wherein at least a part of the outer periphery of the diaphragm is the An adhesive protrudes from the frame member toward the outside of the frame, and an adhesive is provided from the protruding diaphragm to the outer surface of the frame member. sound generator, wherein there Rukoto. The frame member includes a first frame member and a second frame member, and a first adhesive is provided from one main surface of the protruding diaphragm to the outer surface of the first frame member. The second adhesive is provided from the other main surface of the protruding diaphragm to the outer surface of the second frame member, and the adhesive surface of the first adhesive on the outer surface of the first frame member is provided. The sound generator according to claim 1, wherein a height and a height of an adhesive surface of the second adhesive on an outer surface of the second frame member are different.   A diaphragm, a frame member that supports the outer periphery of the diaphragm, and an exciter provided on the diaphragm in the frame of the frame member, wherein at least a part of the outer periphery of the diaphragm is the It protrudes from the frame member toward the outside of the frame, an adhesive is provided from the protruding diaphragm to the outer surface of the frame member, and the frame member is composed of a first frame member and a second frame member, The first adhesive is provided from one main surface of the projecting diaphragm to the outer surface of the first frame member, and the second frame member is disposed from the other main surface of the projecting diaphragm. A second adhesive is provided over the outer surface, and the height of the adhesive surface of the first adhesive on the outer surface of the first frame member and the adhesion of the second adhesive on the outer surface of the second frame member. An acoustic generator characterized in that the height of the surface is different. The outer peripheral portion of the diaphragm protrudes toward the outside the frame from the frame member over the entire periphery, claims 1 to, characterized in that the adhesive toward the outer surface of the frame member from the diaphragm that protrudes is provided Item 4. The sound generator according to any one of Items 3 .   An acoustic generator comprising: the acoustic generator according to any one of claims 1 to 4; and a housing that accommodates the acoustic generator.   A sound generator according to any one of claims 1 to 4, an electronic circuit connected to the sound generator, and a housing that houses the electronic circuit and the sound generator. Features electronic equipment.

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