WO2014091833A1

WO2014091833A1 - Acoustic generator, acoustic generation device, and electronic apparatus

Info

Publication number: WO2014091833A1
Application number: PCT/JP2013/079530
Authority: WO
Inventors: 神谷　哲; 寺園　正喜
Original assignee: 京セラ株式会社
Priority date: 2012-12-10
Filing date: 2013-10-31
Publication date: 2014-06-19

Abstract

[Problem] To obtain frequency characteristics at a favorable sound pressure. [Solution] This embodiment of an acoustic generator is provided with an oscillating body, an exciter, and a damping material. The exciter is provided on the oscillating body. The damping material is attached in a manner so as to be integrated with the oscillating body. Also, when the oscillating body is seen in a plan view, with respect to the center of gravity or axis of symmetry of the figure depicted by the contour of one member of either the exciter or the damping material, the other is disposed in a manner so that the center of gravity or axis of symmetry of the figure depicted by the contour of the other member does not match.

Description

SOUND GENERATOR, SOUND GENERATOR, AND ELECTRONIC DEVICE

The disclosed embodiment relates to a sound generator, a sound generation device, and an electronic apparatus.

Conventionally, an acoustic generator using an actuator is known. For example, Patent Document 1 describes a sound generator that outputs a sound by vibrating a diaphragm by applying a voltage to a piezoelectric element attached to the diaphragm and causing it to vibrate.

Japanese Patent Laid-Open No. 2004-23436

However, since the above-described conventional sound generator actively uses the resonance of the diaphragm, the frequency characteristics of the sound pressure have a peak (a portion where the sound pressure is higher than the surroundings) and a dip (the sound pressure is higher than the surroundings). There is a problem that it is difficult to obtain a high-quality sound quality.

One aspect of the embodiments has been made in view of the above, and an object thereof is to provide an acoustic generator, an acoustic generator, and an electronic apparatus that can obtain a favorable frequency characteristic of sound pressure.

The acoustic generator according to one aspect of the embodiment includes a vibrating body, an exciter, and a damping material. The exciter is provided on the vibrating body. The damping material is attached so as to be integrated with the vibrating body. When the vibrator is viewed in plan, the exciter and the damping material have the symmetry axis or center of gravity of the figure drawn by the outline of the other member with respect to the symmetry axis or center of gravity of the figure drawn by the outline of one of the members. They are arranged so that they do not match.

According to one aspect of the embodiment, a favorable sound pressure frequency characteristic can be obtained.

FIG. 1A is an explanatory diagram in plan view of the sound generator according to the first embodiment. 1B is a cross-sectional view taken along line A-A ′ of FIG. 1A. FIG. 2 is an explanatory view in plan view for explaining the arrangement of the damping material. FIG. 3 is a block diagram of the sound generator. FIG. 4 is a block diagram of the electronic device. FIG. 5A is an explanatory diagram in a plan view of an acoustic generator according to a first modification example of the first embodiment. FIG. 5B is an explanatory diagram in a plan view of an acoustic generator according to a second modification example of the first embodiment. FIG. 6 is an explanatory diagram in plan view of the sound generator according to the second embodiment. FIG. 7 is an explanatory diagram in plan view of the sound generator according to the first modification of the second embodiment. FIG. 8A is an explanatory diagram in plan view of an acoustic generator according to a second modification of the second embodiment. FIG. 8B is an explanatory diagram in a plan view of an acoustic generator according to a third modification of the second embodiment. FIG. 8C is an explanatory diagram of the acoustic generator according to the fourth modification example of the second embodiment in plan view. FIG. 9 is an explanatory diagram in plan view of the sound generator according to the third embodiment. FIG. 10 is an explanatory diagram in plan view of the sound generator according to the fourth embodiment.

Hereinafter, embodiments of a sound generator, a sound generation device, and an electronic device disclosed in the present application will be described with reference to the accompanying drawings. In addition, this invention is not limited by each embodiment shown below.
(First embodiment)
The configuration of the sound generator according to the first embodiment will be described with reference to FIGS. 1A and 1B.

The sound generator 1 according to the first embodiment is a so-called piezoelectric speaker, and has a configuration for generating sound pressure using a resonance phenomenon of a vibrating body. Specifically, as shown in FIGS. 1A and 1B, the acoustic generator 1 includes a frame body 10, a vibrating body 20 stretched on the frame body 10, and a piezoelectric element provided on the vibrating body 20. The vibration element 30 and the damping material 50 are provided.

1A is an explanatory diagram in a plan view of the sound generator 1 according to the first embodiment viewed from a direction perpendicular to the main surface of the vibrating body 20, and FIG. 1B is an AA ′ diagram in FIG. 1A. It is line sectional drawing. In FIG. 1B, in order to facilitate understanding, the sound generator 1 is shown expanded and deformed in the vertical direction.

The vibrating body 20 can be formed using various materials such as resin, metal, and paper. For example, the thin plate-like vibrating body 20 can be made of a resin film made of polyethylene, polyimide, polypropylene, or the like having a thickness of 10 to 200 μm. Since the resin film is a material having a lower elastic modulus and mechanical Q value than a metal plate or the like, the vibration body 20 is made of a resin film, so that the vibration body 20 bends and vibrates with a large amplitude, thereby reducing the sound pressure. It is possible to reduce the difference between the resonance peak and the dip by widening the width of the resonance peak and reducing the height in the frequency characteristics. A composite of metal and resin may be used as the vibrating body 20.

The frame body 10 plays a role of holding the vibrating body 20 and forming a fixed end of vibration. For example, as shown in FIG. 1B, a frame body 10 is configured by vertically joining together an upper frame member 11 and a lower frame member 12 that are rectangular. And the outer peripheral part of the vibrating body 20 which consists of a resin film is pinched | interposed between the upper frame member 11 and the lower frame member 12, and it fixes in the state which gave predetermined tension. Therefore, the acoustic generator 1 includes the vibrating body 20 with little deformation such as deflection even when used for a long time.

The thickness and material of the upper frame member 11 and the lower frame member 12 constituting the frame body 10 are not particularly limited, but in the first embodiment, because of excellent mechanical strength and corrosion resistance, For example, a stainless steel material having a thickness of 100 to 5000 μm is used.

The piezoelectric vibration element 30 includes a laminated body 33,

surface electrode layers

34 and 35 formed on the upper and lower surfaces of the laminated body 33, and an external surface formed on the side surface where the end face of the internal electrode layer 32 of the laminated body 33 is exposed.

Electrodes

36 and 37 are provided.

Lead terminals

38 and 39 are connected to the

external electrodes

36 and 37.

The laminated body 33 is formed by alternately laminating four

piezoelectric layers

31a, 31b, 31c, 31d made of ceramics and three internal electrode layers 32. The piezoelectric vibration element 30 has a rectangular main surface on the upper surface side and the lower surface side, and the

piezoelectric layers

31a and 31b and the

piezoelectric layers

31c and 31d are polarized in different directions in the thickness direction, respectively. The

piezoelectric layers

31b and 31c are polarized in the same direction.

Therefore, when a voltage is applied to the piezoelectric vibration element 30 via the

lead terminals

38 and 39, for example, the lower surface side of the piezoelectric vibration element 30, in other words, the

piezoelectric layers

31c and 31d on the vibration body 20 side contract, while the upper surface The

piezoelectric layers

31a and 31b on the side are deformed so as to extend. As described above, the

piezoelectric layers

31a and 31b on the upper surface side of the piezoelectric vibration element 30 and the

piezoelectric layers

31c and 31d on the lower surface side exhibit opposite expansion and contraction behavior, and as a result, the piezoelectric vibration element 30 is bent by a bimorph type. By vibrating, a certain vibration can be given to the vibrating body 20 to generate a sound.

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

Here, as a material constituting the

piezoelectric layers

31a, 31b, 31c, 31d, conventionally used are lead-free piezoelectric materials such as lead zirconate titanate, Bi layered compounds, and tungsten bronze structure compounds. Piezoelectric ceramics can be used.

The material of the internal electrode layer 32 is mainly composed of a metal, for example, silver and palladium. The internal electrode layer 32 may contain ceramic components constituting the

piezoelectric layers

31a, 31b, 31c, and 31d, whereby the

piezoelectric layers

31a, 31b, 31c, and 31d and the internal electrode layers 32 and 32 are included. , 32 can be obtained, and the piezoelectric vibration element 30 in which the stress due to the difference in thermal expansion is reduced can be obtained.

Further, the surface electrode layers 34 and 35 and the

external electrodes

36 and 37 are mainly composed of metal such as silver. Moreover, you may contain a glass component. By containing the glass component, it is possible to obtain a strong adhesion between the

piezoelectric layers

31a, 31b, 31c, 31d and the internal electrode layer 32 and the surface electrode layers 34, 35 or the

external electrodes

36, 37. . The glass component content may be, for example, 20% by volume or less.

Further, as the wiring connected to the

lead terminals

38 and 39, in order to reduce the height of the piezoelectric vibration element 30, it is preferable to use flexible wiring in which a metal foil such as copper or aluminum is sandwiched between resin films.

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

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

The damping material 50 is formed in a substantially rectangular parallelepiped shape, for example. In the first embodiment, two damping members 50 having the same shape are disposed on both the left and right sides (Y-axis negative direction side and Y-axis positive direction side) of the piezoelectric vibration element 30. Further, as shown in FIG. 1B, each damping material 50 is integrated with the vibrating body 20, the piezoelectric vibrating element 30, and the coating layer 40 by being attached to the surface of the coating layer 40 via an adhesive 60.

Thus, by providing the damping material 50, the region in the vibrating body 20 in which the damping material 50 is disposed receives vibration loss due to the damping material 50 through the coating layer 40, thereby suppressing the resonance phenomenon. It becomes. That is, since the difference between the resonance peak and the dip can be reduced and the frequency characteristic of the sound pressure can be flattened, a favorable frequency characteristic of the sound pressure can be obtained.

Further, when the vibrating body 20 is viewed in plan, the exciter (piezoelectric vibration element 30) and the damping material 50 have the contour of the other member with respect to the axis of symmetry or the center of gravity of the figure drawn by the contour of one of the members. It was determined that the symmetry axis or the center of gravity of the figure to be drawn was not matched. Here, when one member is an exciter (piezoelectric vibration element 30), the other member is a damping material 50. When one member is a damping material 50, the other member is an exciter (piezoelectric vibration element 30). It is.

For example, in the first embodiment, the plurality of damping materials 50 are arranged such that the composite vibration body constituted by the vibration body 20, the piezoelectric vibration element 30, the coating layer 40, and the damping material 50 is asymmetric as a whole. Thus, the degenerated vibration mode is dispersed into a plurality of vibration modes to generate a plurality of resonance peaks.

This point will be specifically described with reference to FIG. FIG. 2 is an explanatory diagram in plan view for explaining the arrangement of the damping material 50. 1A, 1B and FIG. 2 illustrate two damping members 50, the number is not limited.

As shown in FIG. 2, the two damping members 50 describe the outline of the piezoelectric vibration element 30 when the vibrating body 20 is viewed in a plan view from a direction perpendicular to the main surface of the vibrating body 20 (Z-axis direction in the drawing). They are arranged so as to be asymmetric with respect to the symmetry axis of the figure. More specifically, the two damping materials 50 are arranged at a position where the rotational symmetry axis a2 of the two damping materials 50 does not coincide with the rotational symmetry axis a1 of the piezoelectric vibration element 30.

Thereby, the two damping members 50 are arranged in a non-rotational symmetry with respect to the rotational symmetry axis a1 of the piezoelectric vibration element 30. As a result, the composite vibration body constituted by the vibration body 20, the piezoelectric vibration element 30, the coating layer 40, and the damping material 50 becomes asymmetric as a whole. Thereby, the degeneration of the vibration mode can be solved and dispersed in a plurality of vibration modes.

Therefore, according to the sound generator 1 according to the first embodiment, it is possible to reduce the peak level of the resonance frequency and obtain a favorable sound pressure frequency characteristic with small fluctuation. In particular, since the frequency characteristics of the sound pressure in the middle range can be made close to flat, good sound quality can be obtained.

Further, the two damping members 50 are both with respect to the other symmetry axes of the piezoelectric vibration element 30 (longitudinal line symmetry axis L shown in FIG. 5A and short line symmetry axis W shown in FIG. 5B). Are also arranged axisymmetrically with respect to each other. This also makes it possible to reduce the symmetry of the composite vibration body constituted by the vibration body 20, the piezoelectric vibration element 30, the coating layer 40, and the damping material 50.

In the first embodiment, the position of the rotational symmetry axis a1 of the piezoelectric vibration element 30 is assumed to coincide with the center of gravity of the piezoelectric vibration element 30. That is, since the two damping materials 50 are arranged in a non-rotationally symmetrical manner with respect to the center of gravity of the piezoelectric vibration element 30, the vibration body 20, the piezoelectric vibration element 30, the coating layer 40, and the damping material are also arranged by this. The symmetry of the composite vibrator constituted by 50 can be lowered.

In this specification, “the axis of symmetry of the piezoelectric vibration element 30” means the symmetry of the figure drawn by the outline of the piezoelectric vibration element 30 when the vibration body 20 is viewed in a plan view from a direction perpendicular to the main surface of the vibration body 20. It means the axis. Further, “the center of gravity of the piezoelectric vibration element 30” means the center of gravity (center) of a figure drawn by the outline of the piezoelectric vibration element 30 or the center of gravity (center of mass) of the piezoelectric vibration element 30 itself when viewed in plan.

As described above, by arranging the plurality of damping members 50 asymmetrically with respect to the axis of symmetry or the center of gravity of the piezoelectric vibration element 30, good sound pressure can be obtained.

Here, an example in which the two damping members 50 are arranged asymmetrically with respect to all three symmetry axes and the center of gravity of the piezoelectric vibration element 30 is shown. However, the two damping members 50 may be asymmetric with respect to any of the three symmetry axes and the center of gravity of the piezoelectric vibration element 30. For example, the two damping members 50 are arranged at positions that are non-rotationally symmetric with respect to the rotational symmetry axis a1 of the piezoelectric vibration element 30 but are symmetric with respect to the line symmetry axis L or the line symmetry axis W. Also good. Further, the two damping members 50 are non-axisymmetric with respect to the line symmetry axis L or the line symmetry axis W of the piezoelectric vibration element 30, but may be arranged at positions that are rotationally symmetric with respect to the rotation symmetry axis a <b> 1. Good.

The damping material 50 may be any member that has mechanical loss, but is preferably a member having a high mechanical loss factor, in other words, a low mechanical quality factor (so-called mechanical Q). Such a damping material 50 can be formed using various elastic bodies, for example, but since it is desirable that it is soft and easily deformed, it can be suitably formed using a rubber material such as urethane rubber. In particular, a porous rubber material such as urethane foam can be suitably used.

Here, an example in which the rotational symmetry axis a1 of the piezoelectric vibration element 30 and the center of gravity of the piezoelectric vibration element 30 coincide with each other is shown, but the rotation symmetry axis a1 of the piezoelectric vibration element 30 and the center of gravity of the piezoelectric vibration element 30 are It doesn't necessarily need to match. If these do not match, the plurality of damping members 50 may be disposed asymmetrically with respect to either the symmetry axis or the center of gravity of the piezoelectric vibration element 30.

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

As shown in FIG. 3, the acoustic generator 4 can be configured by housing the acoustic generator 1 having the above-described configuration in a resonance box 400. The resonance box 400 is a housing that houses the sound generator 1, and resonates the sound emitted from the sound generator 1 and radiates it as sound waves from the housing surface. Such a sound generator 4 can be used alone as a speaker, and can be suitably incorporated into various electronic devices 2, for example.

As described above, since the difference between the resonance peak and the dip in the frequency characteristic of sound pressure, which is disadvantageous in the piezoelectric speaker, can be reduced, the sound generator 1 according to the present embodiment can be used for a mobile phone or a thin television. Alternatively, it can be suitably incorporated into the electronic device 2 such as a tablet terminal.

Note that the electronic device 2 to which the sound generator 1 can be incorporated is not limited to the above-described mobile phone, flat-screen TV, tablet terminal, and the like, and for example, a refrigerator, a microwave oven, a vacuum cleaner, a washing machine, and the like. Conventionally, home appliances that have not been focused on sound quality are also included.

Here, the electronic device 2 including the above-described sound generator 1 will be briefly described with reference to FIG. FIG. 4 is a block diagram of the electronic device 2. The electronic device 2 includes the acoustic generator 1 described above, an electronic circuit connected to the acoustic generator 1, and a housing 200 that houses the acoustic generator 1 and the electronic circuit.

Specifically, as illustrated in FIG. 4, the electronic device 2 includes an acoustic generator 1, an electronic circuit including a control circuit 21, a signal processing circuit 22, and a wireless circuit 23 as an input device, an antenna 24, and these And a housing 200 for storing the. Although the wireless input device is shown in FIG. 4, it can be provided as a signal input by normal electric wiring.

In addition, description was abbreviate | omitted here about the other electronic member (for example, devices and circuits, such as a display, a microphone, a speaker) with which the electronic device 2 is provided. Moreover, although one acoustic generator 1 was illustrated in FIG. 4, two or more acoustic generators 1 and other oscillators may be provided.

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

In this manner, the electronic device 2 shown in FIG. 4 incorporates the small and thin acoustic generator 1 and reduces the difference between the resonance peak and the dip to suppress the frequency fluctuation as much as possible. It is possible to improve the sound quality as a whole even in a high sound region including a low sound region having a low sound level.

In FIG. 4, the electronic device 2 in which the sound generator 1 is directly mounted is illustrated as the sound output device. However, as the sound output device, for example, a sound generator 4 in which the sound generator 1 is housed in a housing is mounted. It may be the configuration.

By the way, the arrangement example of the damping material 50 that lowers the symmetry of the composite vibration body constituted by the vibration body 20, the piezoelectric vibration element 30, the coating layer 40, and the damping material 50 is not limited to the one shown in FIG. . Another arrangement example of the damping material 50 will be described with reference to FIGS. 5A and 5B. 5A and 5B are explanatory views of the sound generator according to the first and second modifications of the first embodiment in plan view.

5A shows the symmetry axis in the longitudinal direction of the piezoelectric vibration element 30 as the symmetry axis L, and FIG. 5B shows the symmetry axis in the short direction of the piezoelectric vibration element 30 as the symmetry axis W. The symmetry axis L and the symmetry axis W may be shown in other drawings used in the description below.

In the acoustic generator 1-1 shown in FIG. 5A, the two damping members 50 are arranged at positions that are asymmetric with respect to the longitudinal symmetry axis L of the piezoelectric vibration element 30. Thereby, the symmetry of the composite vibrating body constituted by the vibrating body 20, the piezoelectric vibrating element 30, the coating layer 40, and the damping material 50 can be lowered.

Further, in the acoustic generator 1-2 shown in FIG. 5B, the two damping members 50 are arranged at positions that are asymmetric with respect to the symmetry axis W in the short direction of the piezoelectric vibration element 30. Thereby, the symmetry of the composite vibrating body constituted by the vibrating body 20, the piezoelectric vibrating element 30, the coating layer 40, and the damping material 50 can be lowered.

2, 5A, and 5B are asymmetrical with respect to any of the three symmetry axes of the piezoelectric vibration element 30, and also with respect to the center of gravity of the piezoelectric vibration element 30. A plurality of damping materials 50 are arranged so as to be asymmetric. As described above, by arranging the plurality of damping members 50 asymmetrically with respect to all the symmetry axes and the center of gravity of the piezoelectric vibration element 30, the symmetry of the composite vibration body can be further reduced. However, the plurality of damping members 50 may be asymmetric with respect to at least one of the symmetry axis and the center of gravity of the piezoelectric vibration element 30.
(Second Embodiment)
Next, the configuration of the sound generator according to the second embodiment will be described with reference to FIG. FIG. 6 is an explanatory diagram in plan view of the sound generator according to the second embodiment.

As shown in FIG. 6, the sound generator 1 </ b> A according to the second embodiment is replaced with a damping material instead of one of the two damping materials 50 included in the sound generator 1 according to the first embodiment. 50a. The area of the damping material 50 a when the vibrating body 20 is viewed in plan is smaller than that of the damping material 50.

FIG. 6 shows a case where two damping members 50 are arranged at positions that are rotationally symmetric with respect to the rotational symmetry axis a <b> 1 of the piezoelectric vibration element 30. In addition, in FIG. 6, one of the damping materials 50 in such an assumption is shown by the broken-line rectangle which abbreviate | omitted the code | symbol.

Under this assumption, two damping members 50 are arranged symmetrically with respect to the rotational symmetry axis a1 of the piezoelectric vibration element 30. For example, one of the damping members 50 indicated by a broken line is By making the damping material 50 a smaller in area in plan view than the other damping material 50, the symmetry of the composite vibration body constituted by the vibration body 20, the piezoelectric vibration element 30, the coating layer 40 and the damping material 50 is increased. Can be lowered.

Thus, by making the area of at least one damping material in plan view different from the area of other damping materials in plan view, the symmetry of the composite vibrator can be lowered. Therefore, it is possible to obtain a sound generator having a good sound pressure frequency characteristic in which the vibration mode degeneration can be solved and dispersed, and the sound pressure fluctuation is small.

Moreover, in the acoustic generator 1A according to the second embodiment, the damping

materials

50 and 50a having different areas are arranged at positions facing each other with the piezoelectric vibration element 30 interposed therebetween. Thus, by making the areas of the damping

materials

50 and 50a facing each other across the piezoelectric vibration element 30 different from each other, for example, when the areas of the adjacent damping materials are made different, the symmetry of the composite vibrator is further reduced. can do.

Furthermore, as shown in FIG. 6, by arranging damping materials having different areas in the longitudinal direction of the vibrating body 20, the symmetry of the composite vibrating body is more effective than in the case where the damping material is disposed in the short direction. Can be lowered.

FIG. 6 shows an example in which the area of the damping material in plan view is different, but this is not limiting, and the shape of the damping material in plan view may be different. This point will be described with reference to FIG. FIG. 7 is an explanatory diagram in plan view of the sound generator according to the first modification of the second embodiment.

As shown in FIG. 7, in the sound generator 1A-1 according to the first modification, one of the damping materials 50 indicated by the broken line is replaced with the other damping material 50 under the same assumptions as in FIG. The damping material 50b has a different planar shape. Thereby, the symmetry of the composite vibration body constituted by the vibration body 20, the piezoelectric vibration element 30, the coating layer 40, and the damping material 50 can be lowered.

In this way, the planar shape of the at least one damping material 50b (the shape when seen in a plan view from the direction perpendicular to the main surface of the vibrating body 20) is different from the planar shape of the other damping materials 50, thereby combining The symmetry of the vibrating body can be lowered. Therefore, it is possible to obtain the sound generator 1A-1 having a good sound pressure frequency characteristic in which the vibration mode degeneration can be solved and dispersed, and the fluctuation of the sound pressure is small.

Next, further modifications of the sound generator 1A according to the second embodiment will be described with reference to FIGS. 8A to 8C. 8A to 8C are explanatory views in plan view of the acoustic generators according to second to fourth modifications of the second embodiment, respectively. 8A to 8C show an example in which four damping materials are arranged.

As shown in FIG. 8A, in the acoustic generator 1A-2 according to the second modified example, when the vibrating body 20 is viewed in plan, the upper side (X-axis negative direction side) and the lower side ( Two damping materials are arranged side by side on the X-axis positive direction side). Specifically, the damping material 50d and the damping material 50e are arranged side by side on the upper side of the piezoelectric vibration element 30, and the damping material 50f and the damping material 50g are arranged on the lower side of the piezoelectric vibration element 30.

As shown in FIG. 8A, the damping

materials

50d and 50e have different areas when the vibrating body 20 is viewed in plan, and the damping

materials

50f and 50g also have different areas when the vibrating body 20 is viewed in plan. .

Thus, by arranging the damping materials having different areas side by side on one side of the piezoelectric vibration element 30, compared to the case of arranging the damping materials having the same area side by side on one side of the piezoelectric vibration element 30, the composite The symmetry of the vibrating body can be lowered.

Also, as shown in FIG. 8B, the sound generator 1A-3 according to the third modification includes four damping materials 50h to 50k. These damping materials 50h to 50k have different areas in plan view. Thus, by making the areas of all the damping materials 50h to 50k different, the symmetry of the composite vibrator can be further reduced.

Further, as shown in FIG. 8C, the sound generator 1A-4 according to the third modification includes four damping materials 50l to 50o. These damping materials 50l to 50o are all different in shape in plan view. Thus, by making all the four damping members 50l to 50o different in shape, the symmetry of the composite vibrator can be further reduced.
(Third embodiment)
Next, an acoustic generator according to the third embodiment will be described with reference to FIG. FIG. 9 is an explanatory diagram in plan view of the sound generator according to the third embodiment.

As shown in FIG. 9, the acoustic generator 1B according to the third embodiment differs from the above-described embodiments in that it includes one damping material 50p and a plurality of piezoelectric vibration elements (here, two

Piezoelectric vibration elements

30a and 30b).

Here, in FIG. 9, the arrangement of the damping material 50p is assumed by broken lines so that the two

piezoelectric vibration elements

30a and 30b are symmetrical with respect to the damping material 50p. That is, when the vibrating body 20 is viewed in plan, the symmetry axis of the figure drawn by the outline of the damping material 50p indicated by the broken line (rotation symmetry axis a3, longitudinal line symmetry axis L1, transverse direction line symmetry axis W1) The

piezoelectric vibration elements

30a and 30b are arranged so as to be symmetric with respect to each other.

In the third embodiment, the position of the rotational symmetry axis a3 of the damping material 50p is assumed to coincide with the center of gravity of the damping material 50p. Accordingly, the two

piezoelectric vibration elements

30a and 30b are arranged in rotational symmetry with respect to the center of gravity of the damping material 50p indicated by a broken line.

As described above, under this assumption, the two

piezoelectric vibration elements

30a and 30b are arranged symmetrically with respect to the axis of symmetry or the center of gravity of the damping material 50p. By shifting the position from the position indicated by, the symmetry of the composite vibration body constituted by the vibration body 20, the

piezoelectric vibration elements

30a and 30b, the coating layer 40, and the damping material 50p can be lowered.
(Fourth embodiment)
Next, an acoustic generator according to the fourth embodiment will be described with reference to FIG. FIG. 10 is an explanatory diagram in plan view of the sound generator according to the fourth embodiment.

As shown in FIG. 10, the sound generator 1C according to the fourth embodiment includes one piezoelectric vibration element 30c and one damping material 50q.

Here, in FIG. 10, the arrangement of the damping material 50q that is symmetric with respect to the piezoelectric vibration element 30c is indicated by a broken line. In other words, the damping material 50q indicated by the broken line shows the symmetry axis (rotation symmetry axis a4, longitudinal line symmetry axis L2, longitudinal direction line symmetry axis W2) of the piezoelectric vibration element 30c when the vibrating body 20 is viewed in plan. ) With respect to each other.

In the fourth embodiment, it is assumed that the position of the rotational symmetry axis a4 of the piezoelectric vibration element 30c coincides with the center of gravity of the piezoelectric vibration element 30c. Therefore, the damping material 50q indicated by the broken line is disposed rotationally symmetrically with respect to the center of gravity of the piezoelectric vibration element 30c.

As described above, under such an assumption, the damping material 50q is arranged symmetrically with respect to the symmetry axis or the center of gravity of the piezoelectric vibration element 30c. For example, the damping material 50q is located from the position indicated by the broken line. By shifting, the symmetry of the composite vibration body constituted by the vibration body 20, the piezoelectric vibration element 30c, the coating layer 40, and the damping material 50q can be lowered.

In each of the above-described embodiments, an example in which one of the piezoelectric vibration element and the damping material is singular has been described. However, the acoustic generator is provided with a plurality of piezoelectric vibration elements and a plurality of damping materials. May be. Further, although the piezoelectric vibration element is rectangular in plan view, the piezoelectric vibration element may be square.

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

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

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

DESCRIPTION OF SYMBOLS 1 Sound generator 2 Electronic device 4 Sound generator 10 Frame body 20 Vibrating body 30 Piezoelectric vibration element 40 Coating layer 50 Damping material 60 Adhesive

Claims

A vibrating body,
An exciter provided on the vibrator;
A damping material attached to be integrated with the vibrating body,
When the vibrating body is viewed in plan, the exciter and the damping material are arranged so that the symmetry axis or center of gravity of the figure drawn by the outline of the other member with respect to the symmetry axis or center of gravity of the figure drawn by the outline of one of the members The sound generator is characterized by being arranged so as not to match.
One of the exciter and the damping material is provided, and the other member is provided in plural, and the other member is provided with respect to the symmetry axis or center of gravity of the figure drawn by the outline of the one member. The sound generators according to claim 1, wherein are arranged asymmetrically with respect to each other.
The one member is the exciter, the plurality of other members are the damping materials, and the plurality of damping materials do not rotate with respect to the axis of symmetry or the center of gravity of the figure drawn by the outline of the exciter The sound generator according to claim 2, wherein the sound generator is arranged symmetrically or non-linearly symmetrically.
The one member is the damping material, the plurality of the other members are the exciters, and the plurality of exciters are not rotated with respect to the symmetry axis or the center of gravity of the figure drawn by the outline of the damping material. The sound generator according to claim 2, wherein the sound generator is arranged symmetrically or non-linearly symmetrically.
The sound according to any one of claims 2 to 4, wherein at least one of the plurality of other members has an area different from that of the other member when the vibrating body is viewed in plan. Generator.
6. The sound generator according to claim 5, wherein the other members having different areas are arranged at positions facing each other with the one member interposed therebetween.
The acoustic generator according to claim 5 or 6, wherein a plurality of the other members having different areas are arranged side by side on one side of the one member.
The acoustic according to any one of claims 5 to 7, wherein at least one of the plurality of other members has a shape different from that of the other member when the vibrating body is viewed in plan. Generator.
The sound generator according to any one of claims 5 to 8, wherein the areas of all the other members are different.
The acoustic generator according to any one of claims 1 to 9, wherein the exciter is a bimorph type laminated piezoelectric vibration element.
An acoustic generator according to any one of claims 1 to 10;
A sound generation device comprising: a housing that houses the sound generator.
An acoustic generator according to any one of claims 1 to 10;
An electronic circuit connected to the acoustic generator;
A housing for housing the electronic circuit and the acoustic generator;
An electronic apparatus having a function of generating sound from the sound generator.