JP6208595B2 - Sound generator, sound generator, electronic equipment - Google Patents

Description

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

  Conventionally, a speaker in which a piezoelectric element is attached to a diaphragm is known (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 2004-23436

  However, the above-described conventional speaker has a problem that distortion is large and sound quality is poor.

  The present invention has been devised in view of such problems in the prior art, and the purpose thereof is an acoustic generator capable of generating high-quality sound with low distortion, and using the same, An object is to provide a sound generator and an electronic device.

The acoustic generator according to the present invention includes a plurality of exciters that vibrate when an electric signal is input thereto, and the plurality of exciters are attached to the main surface on one side, and vibrate due to the vibrations of the plurality of exciters. A vibration body, a resin layer provided on one main surface of the vibration body so as to embed the plurality of exciters, and attached to a main surface on one side of the vibration body via a resin layer, or A damping material directly attached to the other main surface of the vibrating body, and the plurality of exciters include a first exciter and a second exciter, and the damping The material includes a first portion that overlaps with the first exciter when viewed from the thickness direction of the vibrating body, and a portion that overlaps with the second exciter when viewed from the thickness direction of the vibrating body. A second portion, and a connecting portion for connecting the first portion and the second portion It characterized in that it has the a.

  The sound generator of the present invention includes the sound generator and an enclosure attached to the sound generator.

  The electronic device of the present invention includes at least the sound generator and an electronic circuit connected to the sound generator, and has a function of generating sound from the sound generator. And

  The sound generator, sound generator, and electronic device of the present invention can generate high-quality sound with low distortion.

It is a top view showing typically the sound generator of a 1st embodiment of the present invention. It is a top view showing typically the sound generator of a 1st embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line A-A ′ of FIG. 1. It is a perspective view which shows typically the sound generator of 2nd Embodiment of this invention. It is a block diagram which shows the structure of the electronic device of 3rd Embodiment of this invention. It is a graph which shows the frequency characteristic of the sound pressure of the sound generator of 1st Embodiment of this invention, and the sound generator of a comparative example. It is a graph which shows the frequency characteristic of the distortion rate of the acoustic generator of 1st Embodiment of this invention, and the acoustic generator of a comparative example.

  Hereinafter, a sound generator, a sound generator, and an electronic device according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, directions are shown using an x-axis, a y-axis, and a z-axis that are orthogonal to each other.

(First embodiment)
FIG. 1 is a plan view schematically showing the sound generator according to the first embodiment of the present invention as seen from the + z direction. FIG. 2 is a plan view schematically showing the sound generator according to the first embodiment of the present invention as seen from the −z direction. 3 is a cross-sectional view taken along line AA ′ in FIG. FIG. 2 shows a state where the resin layer 23 is seen through. As shown in FIGS. 1 to 3, the acoustic generator of the present embodiment includes exciters 11 and 12 (exciter 11 and exciter 12), a film 21, a resin layer 23, and frames 25 a and 25 b (frames). 25a, a frame 25b) and a damping material 31.

  Each of the frames 25a and 25b has a rectangular frame shape. As the frames 25a and 25b, for example, a stainless steel having a thickness of 100 to 1000 μm can be suitably used, but the material and thickness are not particularly limited, and are more difficult to deform than the film 21 and the resin layer 23. If it is good. For example, the frames 25a and 25b can be formed using hard resin, plastic, engineering plastic, ceramics, or the like.

  The film 21 has a film-like (film-like) shape, and can be formed using, for example, a resin such as PET (polyethylene terephthalate) or polyimide. Moreover, the thickness of the film 21 shall be 10-200 micrometers, for example. The film 21 is sandwiched between the frames 25a and 25b at the peripheral portions of the upper and lower main surfaces (both end surfaces in the z-axis direction) in a state where tension is applied in the surface direction (x-axis direction and y-axis direction). It is fixed and supported by the frames 25a and 25b so as to vibrate. And the vibrating body 21a which can vibrate freely is comprised by the part which is located inside frame 25a, 25b in the film 21, and is not pinched | interposed into frame 25a, 25b. That is, the vibrating body 21a has a rectangular film shape (film shape).

  The shapes of the frames 25a and 25b are not limited to a rectangular shape, and may be a circle or a rhombus. When the frame 25b is not provided, for example, the film 21 may be adhered to the surface of the frame 25a in the + z direction. When the frame 25a is not provided, for example, the −25 direction of the frame 25b is used. What is necessary is just to adhere | attach the film 21 on the surface. Moreover, since the vibrating body 21a should just be a film form (film | membrane form) or a thin plate shape, it can replace with the film 21 and can comprise the vibrating body 21a with a thin plate metal, paper, etc. FIG.

The exciters 11 and 12 are attached to the surface of the vibrating body 21a on the −z direction side, and are integrated with the vibrating body 21a. The exciters 11 and 12 are piezoelectric elements having a plate shape in which the upper and lower main surfaces (both end surfaces in the z-axis direction) are rectangular. Although not shown in detail, the exciters 11 and 12 include a laminated body in which piezoelectric layers made of piezoelectric ceramics and internal electrode layers are alternately laminated, and upper and lower surfaces of the laminated body (both ends in the z-axis direction). Surface electrode layer and a pair of terminal electrodes provided on both end faces in the longitudinal direction (x-axis direction) of the laminate. In addition, the surface electrode and the internal electrode layer are alternately drawn out to both end faces in the longitudinal direction (x-axis direction) of the laminate, and are connected to the terminal electrodes, respectively. Then, an electrical signal is applied to the pair of terminal electrodes via a wiring (not shown).

  The exciters 11 and 12 are bimorph piezoelectric elements, and when an electric signal is input, expansion and contraction are reversed between one side and the other side in the thickness direction (z-axis direction) at an arbitrary moment. It is supposed to be. Therefore, the exciters 11 and 12 bend and vibrate in the z-axis direction when an electric signal is input, and vibrate the vibrating body 21a by vibrating itself. Then, sound is generated when the vibrating body 21a vibrates.

  Note that, as the exciters 11 and 12, for example, monomorph type vibration elements configured by bonding a piezoelectric element that receives an electric signal to expand and contract and vibrate and a metal plate may be used. Moreover, the main surface of the exciters 11 and 12 on the film 21 side and the film 21 are bonded to each other with a known adhesive such as an epoxy resin, a silicone resin, or a polyester resin, or a double-sided tape.

  As the piezoelectric layers of the exciters 11 and 12, lead-free piezoelectric materials such as lead zirconate (PZ), lead zirconate titanate (PZT), Bi layered compounds, tungsten bronze structure compounds, etc. are conventionally used. Piezoelectric ceramics can be used. The thickness of one layer of the piezoelectric layer is preferably about 10 to 100 μm, for example.

  As the internal electrode layers of the exciters 11 and 12, various known metal materials can be used. For example, an internal electrode layer containing a metal component made of silver and palladium and a material component constituting the piezoelectric layer can be used, but it may be formed using other materials. The surface electrode layers and the terminal electrodes of the exciters 11 and 12 can be formed using various known metal materials. For example, it can be formed using a material containing a metal component made of silver and a glass component, but may be formed using other materials.

  The resin layer 23 is formed over the entire inside of the frame 25a so as to embed the exciters 11 and 12, and is integrated with the vibrating body 21a and the exciters 11 and 12. The resin layer 23 can be formed using various known materials. For example, a resin such as an acrylic resin or a silicone resin, rubber, or the like can be used. In addition, the thickness of the resin layer 23 is desirably a thickness that completely covers the exciters 11 and 12, but may be formed so as to cover at least a part of the film 21. The resin layer 23 has an effect of improving the sound quality of the sound generated from the sound generator, but is not essential and may be omitted depending on circumstances.

  The damping material 31 is attached to the surface of the vibrating body 21a on the + z direction side, and is integrated with the vibrating body 21a, the exciters 11, 12 and the resin layer 23. Further, the damping material 31 is formed so as to overlap a part of the vibrating body 21a when viewed from the thickness direction (z-axis direction) of the vibrating body 21a. Further, the damping material 31 is viewed from the thickness direction (z-axis direction) of the vibrating body 21a and the portion 31a that overlaps the exciter 11 when viewed from the thickness direction (z-axis direction) of the vibrating body 21a. A portion 31b that overlaps the exciter 12, and a connection portion 31c that connects the portion 31a and the portion 31b. The connection part 31c is a part that is located between the part 31a and the part 31b and connects the part 31a and the part 31b.

The damping material 31 only needs to have a mechanical loss, but is desirably a member having a high mechanical loss factor, in other words, a low mechanical quality factor (so-called mechanical Q). Such a damping material 31 can be formed using various elastic bodies, for example, but since it is desirable that it is soft and easily deformed, a rubber material such as urethane rubber, a soft resin material such as silicone resin, and the like It can form suitably using. In particular, a porous rubber material such as urethane foam can be suitably used. Since the portion to which the damping material 31 is attached receives vibration loss due to the damping material 31, the amplitude of the portion to which the damping material 31 is attached can be reduced.

  The damping material 31 is preferably attached directly to the vibrating body 21a, but is not limited to this. For example, the damping material 31 may be attached to the surface of the resin layer 23. That is, the damping material 31 may be attached to the vibrating body 21 a via the resin layer 23. In some cases, the damping material 31 may be attached to the vibrating body 21 a via the exciters 11 and 12. In this way, the damping material 31 may be attached to the vibrating body 21a via some other object.

  As described above, the sound generator according to the present embodiment is provided with a plurality of exciters (exciter 11 and exciter 12) that vibrate when an electric signal is input thereto, and a plurality of exciters, respectively. A vibration body 21a that vibrates due to the vibration of the vibrator, and a damping material 31 attached to the vibration body 21a. The plurality of exciters includes the exciter 11 and the exciter 12. When viewed from the thickness direction (z-axis direction) of the vibration member 21a, the damping material 31 is a portion 31a that overlaps the exciter 11 when viewed from the thickness direction (z-axis direction) of the vibration member 21a. And a portion 31b which is a portion overlapping with the exciter 12. Thereby, it is possible to generate high-quality sound with small distortion.

  The reason why this effect can be obtained can be estimated as follows. In the acoustic generator of the present embodiment, a plurality of exciters (exciter 11 and exciter 12) are attached to the vibrating body 21a, and the exciter 11 and the exciter 12 vibrate by electric signals. Therefore, it becomes possible to reduce the symmetry in vibration of the vibrating body 21a, and it is possible to reduce a sudden change in sound pressure at a specific frequency due to resonance. In the acoustic generator of this embodiment, the damping material 31 is attached to the vibrating body 21a, and the damping material 31 is a portion that overlaps the exciter 11 when viewed from the thickness direction of the vibrating body 21a. 31a, a portion 31b that overlaps the exciter 12 when viewed from the thickness direction of the vibrating body 21a, and a connection portion 31c that connects the portion 31a and the portion 31b. Thereby, the harmonic distortion can be reduced by reducing the vibration in the vicinity of the exciter 11 and the exciter 12 having a large amplitude in the harmonic. Further, the vibration transmission through the connecting portion 31c occurs between the vicinity of the exciter 11 and the vicinity of the exciter 12, so that the symmetry in the vibration of the vibrating body 21a can be further reduced. As a result, distortion in sound generated from the sound generator can be reduced.

In the acoustic generator of the present embodiment, the connection portion 31c connects the center of gravity 13 of the exciter 11 and the center of gravity 14 of the exciter 12 when viewed from the thickness direction (z-axis direction) of the vibrating body 21a. It is provided at a position that does not overlap the midpoint 15 of the line segment. Thereby, it can reduce that the sound pressure in the low frequency side especially in the sound generated from a sound generator falls. The reason why this effect can be obtained is estimated as follows. A midpoint 15 of a line segment connecting the center of gravity 13 of the exciter 11 and the center of gravity 14 of the exciter 12 when viewed from the thickness direction (z-axis direction) of the vibrating body 21a is the exciter 11, exciter 12, and Are oscillating synchronously, the amplitude of the fundamental mode resonance of the vibrator 21a is large. For this reason, when a damping material is provided in this part, the fundamental mode resonance of the vibrating body 21a is attenuated, and a problem arises in that the sound pressure on the low frequency side in the sound generated from the sound generator is lowered. When the connection portion 31c is viewed from the thickness direction (z-axis direction) of the vibrating body 21a, the connection portion 31c is positioned so as not to overlap the midpoint 15 of the line segment connecting the center of gravity 13 of the exciter 11 and the center of gravity 14 of the exciter 12. By providing, it is possible to attenuate higher-order mode resonance of the vibrating body 21a while reducing attenuation of fundamental mode resonance of the vibrating body 21a. As a result, it is possible to generate sound having a large sound pressure and a small distortion. Thus, it is desirable that the damping material 31 is provided in a portion where the amplitude of the fundamental mode resonance is small and the amplitude of the higher order mode resonance is large in the vibration of the vibrating body 21a.

  In most cases, the center of gravity of the figure drawn by the outline of the exciter 11 when viewed from the thickness direction (z-axis direction) of the vibrating body 21a is viewed from the thickness direction (z-axis direction) of the vibrating body 21a. It may be regarded as the center of gravity 13 of the exciter 11 at the time. Similarly, the center of gravity of the figure drawn by the outline of the exciter 12 when viewed from the thickness direction (z-axis direction) of the vibrating body 21a is excited when viewed from the thickness direction (z-axis direction) of the vibrating body 21a. The center of gravity 14 of the vessel 12 may be considered. For example, when the exciter 11 and the exciter 12 have a rectangular shape when viewed from the thickness direction (z-axis direction) of the vibrating body 21a, the intersection of two diagonal lines in each is defined as the center of gravity of each. You can consider it.

  Moreover, the acoustic generator of this embodiment differs in the area of the part 31a and the area of the part 31b. Thereby, since the symmetry in the vibration of the vibrating body 21a can be further reduced, a sudden change in sound pressure at a specific frequency can be reduced, thereby reducing distortion. However, this is not essential and may not be necessary in some cases.

  Moreover, the acoustic generator of this embodiment differs in the shape of the part 31a and the shape of the part 31b. Thereby, since the symmetry in the vibration of the vibrating body 21a can be further reduced, a sudden change in sound pressure at a specific frequency can be reduced, thereby reducing distortion. However, this is not essential and may not be necessary in some cases.

  In the acoustic generator of the present embodiment, the exciter 11 has a portion 11a that is a portion that does not overlap the damping material 31 when viewed from the thickness direction of the vibrating body 21a. It has the part 12a which is a part which does not overlap with the damping material 31 when it sees from the thickness direction of the vibrating body 21a, and the area of the part 11a and the area of the part 12a differ. Thereby, since the symmetry in the vibration of the vibrating body 21a can be further reduced, a sudden change in sound pressure at a specific frequency can be reduced, thereby reducing distortion. However, this is not essential and may not be necessary in some cases.

  Moreover, the acoustic generator of this embodiment differs in the shape of the part 11a and the shape of the part 12a. Thereby, since the symmetry in the vibration of the vibrating body 21a can be further reduced, a sudden change in sound pressure at a specific frequency can be reduced, thereby reducing distortion. However, this is not essential and may not be necessary in some cases.

  In the acoustic generator of the present embodiment, the exciters 11 and 12 have all the symmetry axes (lines) of the figure drawn by the outline of the vibrating body 21a when viewed from the thickness direction (z-axis direction) of the vibrating body 21a. It is desirable that they be arranged asymmetrically with respect to the symmetry axis of symmetry and the center of rotational symmetry. Thereby, the symmetry in the vibration of the vibrating body 21a can be further reduced. However, this is not essential and may not be.

  The sound generator of this embodiment can be manufactured as follows, for example. First, a binder, a dispersant, a plasticizer, and a solvent are added to the powder of the piezoelectric material and stirred to prepare a slurry. As the piezoelectric material, any of lead-based and non-lead-based materials can be used. Next, the obtained slurry is formed into a sheet shape to produce a green sheet. A conductor paste is printed on the green sheet to form a conductor pattern to be an internal electrode, and the green sheet on which the conductor pattern is formed is laminated to produce a laminated molded body.

Next, this laminated molded body is degreased, fired, and cut into a predetermined size to obtain a laminated body. If necessary, the outer periphery of the laminate is processed. Next, a conductor paste is printed on the main surface in the stacking direction of the laminate to form a conductor pattern to be a surface electrode layer, and the conductor paste is printed on both side surfaces in the longitudinal direction (x-axis direction) of the stack. Thus, a conductor pattern to be a pair of terminal electrodes is formed. And the structure used as the exciters 11 and 12 can be obtained by baking an electrode at predetermined temperature. Thereafter, in order to impart piezoelectricity to the exciters 11 and 12, a direct current voltage is applied through the surface electrode layer or the pair of terminal electrodes to polarize the piezoelectric layers of the exciters 11 and 12. In this way, the exciters 11 and 12 can be obtained.

  Next, the periphery of the film 21 in a tensioned state is fixed by being sandwiched between frames 25a and 25b coated with an adhesive, and the adhesive is cured and joined. Then, the exciters 11 and 12 are bonded to the film 21 with an adhesive on the surface of the vibrating body 21a on the −z direction side, and wiring is connected to the exciters 11 and 12. Then, a resin layer 23 is formed by pouring resin inside the frame 25a and curing it. And the damping material 31 prepared beforehand is joined to the surface of the + z direction side of the vibrating body 21a with an adhesive or an adhesive. In this way, the sound generator of this embodiment can be obtained.

(Second Embodiment)
FIG. 4 is a perspective view showing a sound generator according to the second embodiment of the present invention. In the present embodiment, only differences from the acoustic generator of the first embodiment described above will be described, and the same reference numerals will be given to the same components, and redundant description will be omitted. As shown in FIG. 4, the sound generator of the present embodiment includes a sound generator 29 and an enclosure 27.

  The sound generator 29 generates sound (including sound outside the audible frequency band) when an electric signal is input, and although not shown in detail, is the sound generator of the first embodiment described above. .

  The enclosure 27 has a rectangular parallelepiped box shape. The enclosure 27 has at least one opening, and a sound generator 29 is attached so as to close the opening. Moreover, the enclosure 27 is comprised so that the main surface of the side by which the exciters 11 and 12 of the film 21 are arrange | positioned may be surrounded. The enclosure 27 only needs to have a function of suppressing the wraparound of the sound generated on the back surface side of the sound generator 29 to the front surface side. For this reason, the shape of the enclosure 27 is not limited to a rectangular parallelepiped shape, and may be various shapes such as a conical shape and a spherical shape. Moreover, the enclosure 27 does not need to be box-shaped, and may be a flat baffle, for example. Such an enclosure 27 can be formed using various known materials. For example, the enclosure 27 can be formed using materials such as wood, synthetic resin, and metal.

  Since the sound generator of this embodiment generates sound using the sound generator 29 that is the sound generator of the first embodiment described above, it is possible to generate sound with good sound quality. Moreover, since the sound generator of this embodiment has the enclosure 27, it is also possible to generate sound with better sound quality than when the sound generator 29 is used alone. Instead of the sound generator of the first embodiment, another form of sound generator having the same performance may be used.

(Third embodiment)
FIG. 5 is a block diagram showing a configuration of an electronic apparatus according to the third embodiment of the present invention. As shown in FIG. 5, the electronic device of the present embodiment includes an acoustic generator 29, an electronic circuit 60, a key input unit 50c, a microphone input unit 50d, a display unit 50e, and an antenna 50f. Yes. FIG. 5 is a block diagram assuming an electronic device such as a mobile phone, a tablet terminal, or a personal computer.

The electronic circuit 60 includes a control circuit 50a and a communication circuit 50b. The electronic circuit 60 is connected to the sound generator 29 and has a function of outputting an audio signal to the sound generator 29. The control circuit 50a is a control unit of the electronic device. The communication circuit 50b transmits and receives data through the antenna 50f based on the control of the control circuit 50a.

  The key input unit 50c is an input device of an electronic device and accepts a key input operation by an operator. The microphone input unit 50d is also an input device of an electronic device, and accepts an audio input operation by an operator. The display unit 50e is a display output device of an electronic device, and outputs display information based on the control of the control circuit 50a.

  The sound generator 29 is the sound generator of the first embodiment described above. The sound generator 29 functions as a sound output device in the electronic apparatus, and generates sound (including sound outside the audible frequency band) based on the sound signal input from the electronic circuit 60. The sound generator 29 is connected to the control circuit 50a of the electronic circuit 60, and generates sound by receiving the application of a voltage controlled by the control circuit 50a.

  As described above, the electronic apparatus according to the present embodiment includes at least the sound generator 29 and the electronic circuit 60 connected to the sound generator 29, and has a function of generating sound from the sound generator 29. ing. Since the electronic apparatus of this embodiment generates sound using the sound generator 29 of the first embodiment described above, it can generate sound with good sound quality.

  Examples of the structure of the electronic device include, for example, an electronic circuit 60, a key input unit 50c, a microphone input unit 50d, a display unit 50e, an antenna 50f, and an acoustic generator shown in FIG. 29 may be provided. In addition, as another example of the structure of the electronic device, an electronic device 60, a key input unit 50c, a microphone input unit 50d, a display unit 50e, and an antenna 50f shown in FIG. 29 may be connected via an electrical lead or the like so that an electrical signal can be transmitted.

  Further, the electronic device of the present embodiment does not have to include all of the key input unit 50c, the microphone input unit 50d, the display unit 50e, and the antenna 50f shown in FIG. 5, and the acoustic generator 29 and the electronic circuit 60 at least. In addition, the electronic device may have other components. Furthermore, the electronic circuit 60 is not limited to the electronic circuit 60 having the above-described configuration, and may be an electronic circuit having another configuration.

  Further, the electronic device of the present embodiment is not limited to the above-described electronic devices such as a mobile phone, a tablet terminal, and a personal computer. In various electronic devices having a function of generating sound and sound, such as a television, an audio device, a radio, a vacuum cleaner, a washing machine, a refrigerator, and a microwave oven, the sound generator 29 of the first embodiment described above is used to generate sound. It can be used as a device. Instead of the sound generator of the first embodiment, another form of sound generator having the same performance may be used.

(Modification)
The present invention is not limited to the above-described embodiments, and various changes and improvements can be made without departing from the scope of the present invention.

For example, in the above-described embodiment, an example in which piezoelectric elements are used as the exciters 11 and 12 has been described, but the present invention is not limited to this. Exciters 11 and 12 need only have a function of converting electrical signals into mechanical vibrations, and other ones having a function of converting electrical signals into mechanical vibrations may be used as exciters 11 and 12. I do not care. For example, an electrodynamic exciter, an electrostatic exciter, or an electromagnetic exciter well known as an exciter for vibrating a speaker may be used as the exciters 11 and 12. 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. The electrostatic exciter is composed of two metals facing each other. 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.

  In the above-described embodiment, the example in which the two exciters 11 and 12 are attached to the surface of the film 21 is shown, but the present invention is not limited to this. For example, a larger number of exciters may be attached to the surface of the film 21. In that case, it is desirable that the damping material 31 has a portion that overlaps with all the exciters attached to the vibrating body 21a when viewed from the thickness direction of the vibrating body 21a, thereby reducing the distortion. Can be increased. Also in this case, the damping material 31 does not entirely cover the vibrating body 21a, and is formed so as to overlap with a part of the vibrating body 21a when viewed from the thickness direction of the vibrating body 21a. It is desirable. There may be an exciter that does not overlap with the damping material 31 when viewed from the thickness direction of the vibrating body 21a. In addition to the damping material 31, another damping material may be attached to the vibrating body 21a.

  Next, specific examples of the present invention will be described. The acoustic generator according to the first embodiment shown in FIGS. 1 to 3 was produced and its characteristics were evaluated.

  First, a slurry was prepared by kneading a piezoelectric powder containing lead zirconate titanate (PZT) in which a part of Zr was substituted with Sb, a binder, a dispersant, a plasticizer, and a solvent by ball mill mixing. . And the green sheet was produced by the doctor blade method using the obtained slurry. A conductor paste containing Ag and Pd was applied to the green sheet in a predetermined shape by screen printing to form a conductor pattern serving as an internal electrode layer. And the green sheet in which the conductor pattern was formed, and the other green sheet were laminated | stacked and pressurized, and the lamination molded object was produced. And this laminated molded object was degreased in air | atmosphere at 500 degreeC for 1 hour, Then, it baked in air | atmosphere at 1100 degreeC for 3 hours, and obtained the laminated body.

  Next, both end surface portions in the longitudinal direction of the obtained laminate were cut by dicing, and the tips of the internal electrode layers were exposed on the side surfaces of the laminate. And the conductor paste containing Ag and glass was apply | coated to the both-sides main surface of a laminated body with the screen printing method, and the surface electrode layer was formed. Thereafter, a conductor paste containing Ag and glass was applied to both side surfaces in the longitudinal direction of the laminate by a dipping method, and baked in the atmosphere at 700 ° C. for 10 minutes to form terminal electrodes. This produced the laminated body. The shape of the produced laminate was 14 mm in width, 36 mm in length, and 0.15 mm in thickness. Then, a voltage of 100 V was applied through the terminal electrode for 2 minutes for polarization, and exciters 11 and 12 which were bimorph type stacked piezoelectric elements were obtained.

  Next, a film 21 made of PET having a thickness of 25 μm was prepared, and fixed to the frames 25a and 25b in a state where tension was applied. The frames 25a and 25b were made of stainless steel having a thickness of 0.5 mm. The dimensions of the film 21 in the frames 25a and 25b were 100 mm in length and 60 mm in width. And the exciters 11 and 12 were adhere | attached on the one main surface of the fixed film 21 with the adhesive agent which consists of acrylic resins, and the wiring was connected to the exciters 11 and 12. FIG. Then, an acrylic resin was filled inside the frame 25a so as to have the same height as the frame 25a and solidified to form a resin layer 23.

  Next, the damping material 31 was affixed on the other main surface of the film 21 with a double-sided tape. As the damping material 31, urethane foam having a thickness of 1 mm was used. The shape and attachment position of the damping material 31 were as shown in FIGS.

And the frequency characteristic of sound pressure was measured about the sound which generate | occur | produces from the produced sound generator of 1st Embodiment, and the sound generator of the comparative example which has not attached the damping material 31. FIG. The result is shown in FIG. Moreover, the frequency characteristic of the distortion rate was measured for the sound generated from the sound generator of the first embodiment and the sound generator of the comparative example. The measurement results are shown in FIG. In the graphs shown in FIGS. 6 and 7, the characteristics of the sound generator of the first embodiment are indicated by solid lines, and the characteristics of the sound generator of the comparative example are indicated by dotted lines.

  According to the graphs shown in FIGS. 6 and 7, the sound generated from the sound generator of the first embodiment has a flat frequency characteristic of sound pressure compared to the sound generated from the sound generator of the comparative example. In addition, it can be seen that the distortion rate is small and the sound quality is low and the distortion is good. This confirmed the effectiveness of the present invention.

DESCRIPTION OF SYMBOLS 11, 12: Exciter 21a: Vibrating body 25a, 25b: Frame 27: Enclosure 29: Sound generator 31: Damping material 60: Electronic circuit

Claims (8)

A plurality of exciters that receive electric signals and vibrate;
The plurality of exciters are attached to the main surface on one side, respectively, and a vibrating body that vibrates due to vibration of the plurality of exciters,
A resin layer provided on a principal surface on one side of the vibrator so as to embed the plurality of exciters;
Said one side of the main surface of the vibrating member mounted via the resin layer, or damping material attached directly to the other side of the main surface of the vibrating body,
Have
The plurality of exciters includes a first exciter and a second exciter,
The damping material includes a first portion that overlaps the first exciter when viewed from the thickness direction of the vibrator, and the second exciter when viewed from the thickness direction of the vibrator. An acoustic generator, comprising: a second portion that is an overlapping portion; and a connection portion that connects the first portion and the second portion.   The connection portion is provided at a position that does not overlap a midpoint of a line segment connecting the center of gravity of the first exciter and the center of gravity of the second exciter when viewed from the thickness direction of the vibrating body. The sound generator according to claim 1.   The acoustic generator according to claim 1, wherein an area of the first portion is different from an area of the second portion.   The sound generator according to any one of claims 1 to 3, wherein a shape of the first portion is different from a shape of the second portion. The first exciter has a third portion that is a portion that does not overlap the damping material when viewed from the thickness direction of the vibrating body,
The second exciter has a fourth portion that is a portion that does not overlap the damping material when viewed from the thickness direction of the vibrator,
The sound generator according to any one of claims 1 to 4, wherein an area of the third portion is different from an area of the fourth portion.   The sound generator according to claim 5, wherein a shape of the third portion is different from a shape of the fourth portion.   An acoustic generator comprising: the acoustic generator according to any one of claims 1 to 6; and an enclosure attached to the acoustic generator.   A sound generator according to any one of claims 1 to 6 and an electronic circuit connected to the sound generator, and having a function of generating sound from the sound generator. An electronic device characterized by that.