JP3160271B2 - Piezoelectric speaker, method of manufacturing the same, and speaker system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric speaker used for audio equipment, a method of manufacturing the same, and a speaker system.

[0002]

2. Description of the Related Art The sound reproducing mechanism of a piezoelectric speaker is based on surface resonance. However, since the conventional piezoelectric speaker has a structure in which the peripheral portion of the diaphragm is fixed to the frame, the amplitude of the diaphragm decreases greatly as approaching the peripheral portion of the diaphragm. As a result, in the peripheral portion of the diaphragm, the vibration energy that can be transmitted to the air is greatly reduced. The behavior of such a diaphragm is the same as the behavior of the vibration surface of a drum.

[0003] For this reason, in the conventional piezoelectric speaker, a high sound pressure can be obtained in a high frequency region (high band) that can be reproduced with a small amplitude, whereas in a frequency band (low band) of about 1 kHz or less, a high sound pressure can be obtained. There was a problem that a sufficiently high sound pressure could not be obtained.

For this reason, conventional piezoelectric speakers are used for:
It was limited to tweeters that only handle high frequencies, and speakers for telephone receivers.

FIG. 22 shows a structure of a conventional piezoelectric speaker 220 having a structure in which a diaphragm is sandwiched between resin foams. The piezoelectric speaker 220 includes a metal vibration plate 224, a piezoelectric element 223 formed on the metal vibration plate 224, and a resin foam 222 for fixing a peripheral portion of the metal vibration plate 224.

[0006] The resin foam 222 is a member having flexibility. The resin foam 222 is provided so as to sandwich the metal diaphragm 224.

The piezoelectric speaker 220 has a metal diaphragm 224
Resin foam 2 provided for the purpose of increasing the amplitude of
22 has a contradictory structure that also serves as a support member for fixing the peripheral portion of the metal diaphragm 224. In fact, the role of the resin foam 222 is
Often, the emphasis is on fixing the surrounding area. For this reason, sufficient compliance cannot be obtained.

[0008] The behavior of the diaphragm in the piezoelectric speaker 220 is only about the same as the behavior of the vibrating surface of the drum. Therefore, the problem that it is difficult to reproduce a sound in a low frequency band is the same as that of a conventional piezoelectric speaker having a structure in which a peripheral portion of a diaphragm is fixed to a frame. Further, the piezoelectric speaker 220 has a disadvantage that it is difficult to realize a thin type piezoelectric speaker because the thickness of the piezoelectric speaker is increased by the thickness of the resin foam and the thickness of the frame sandwiching them. I have it.

[0009]

As described above, in the conventional piezoelectric speaker, since the peripheral portion of the diaphragm is fixed to the frame or the resin foam, it is difficult to reproduce sound in a low frequency band. There was a problem. Further, in the conventional piezoelectric speaker, since a strong resonance mode is generated at a specific frequency, there is a problem that a peak dip having a large sound pressure difference appears in acoustic characteristics over a wide frequency band.

[0010] The present invention has been made in view of the above problems, and has as its object to provide a piezoelectric speaker capable of reproducing a sound in a lower frequency band, a method of manufacturing the same, and a speaker system. Another object of the present invention is to provide a piezoelectric speaker that suppresses a peak dip having a large sound pressure difference from appearing in acoustic characteristics, a method of manufacturing the same, and a speaker system.

[0011]

According to the present invention, there is provided a piezoelectric speaker comprising a frame, a diaphragm, a piezoelectric element disposed on the diaphragm, the frame and the diaphragm connected to the frame, There comprising a damper for supporting the diaphragm to allow amplitude linearly, and a formed edge to fill the gap between the damper and the front <br/> SL frame and the vibrating plate, wherein The diaphragm, the damper, and the edge are formed on the same plane, thereby achieving the above object.

According to another aspect of the present invention, there is provided a piezoelectric speaker connected to a frame, a plurality of diaphragms, at least one piezoelectric element disposed on the plurality of diaphragms, and the frame and the plurality of diaphragms. And a plurality of dampers for supporting the plurality of diaphragms so that each of the plurality of diaphragms can linearly oscillate, the plurality of diaphragms and the plurality of
An edge formed so as to fill a gap between the damper and the frame, wherein the plurality of diaphragms, the plurality of dampers and the edge are formed on the same plane, The above object is achieved.

[0013] The at least one piezoelectric element includes a first piezoelectric element and a plurality of second piezoelectric elements, the first piezoelectric element transmitting vibration to the plurality of diaphragms, and Each of the second piezoelectric elements may transmit vibration to a corresponding one of the plurality of diaphragms.

A resin may be formed on at least a part of the surfaces of the plurality of diaphragms.

[0015] A common resin may be used as the resin and the resin used to form the edge.

[0016] The plurality of dampers may include a plurality of portions having different physical characteristics.

[0017] The edge may include a plurality of portions having different physical characteristics.

[0018] The plurality of diaphragms may have different weights from each other.

The plurality of diaphragms may be formed with resins having different thicknesses.

[0020] The plurality of diaphragms may have different thicknesses from each other.

In the method of manufacturing a piezoelectric speaker according to the present invention, a plate is processed to be connected to a frame, a plurality of diaphragms, the frame and the plurality of diaphragms, and each of the plurality of diaphragms is Forming a plurality of dampers for supporting the plurality of diaphragms so as to be capable of linearly oscillating, such that the plurality of diaphragms and the plurality of dampers are on the same plane; and Disposing at least one piezoelectric element on a plate; and
Forming an edge on the same plane to fill a gap between the plurality of dampers and the frame, whereby the object is achieved.

The edge may be formed by attaching a sheet to the plurality of diaphragms.

[0023] The sheet may be a thin film of rubber having elasticity.

The sheet may be formed by impregnating or coating a woven or non-woven fabric having elasticity with a resin having rubber elasticity to perform sealing.

The edge is formed by holding the polymer resin in the gap between the plurality of diaphragms and the frame by utilizing a capillary phenomenon caused by the surface tension of a liquid polymer resin. Is also good.

The polymer resin may be any one of a solvent volatile curing type, a mixed reaction curing type of two or more liquids, and a low temperature reaction type resin.

The polymer resin may be held in the gap using a dipping method or a spin coating method.

[0028] The method may further include, before the step of forming the edge, a step of improving adhesion between the plurality of diaphragms and the polymer resin.

[0029] The method may further include the step of electrically connecting the at least one piezoelectric element.

A speaker system according to the present invention is a speaker system including a plurality of piezoelectric speakers, wherein each of the plurality of piezoelectric speakers is the above-described piezoelectric speaker. Thereby, the above object is achieved.

[0031] The plurality of piezoelectric speakers may have different acoustic characteristics so as to complement peak dips.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

[0033] 1. Construction first piezoelectric speaker shows the structure of a piezoelectric speaker 1a in an embodiment of the present invention.

The piezoelectric speaker 1a includes an outer frame 2a
, An inner frame 2b, diaphragms 4a to 4d, and a piezoelectric element 3 for transmitting vibration to the diaphragms 4a to 4d.

The diaphragm 4a is connected to the inner frame 2b via dampers 5a and 5b. Similarly, the diaphragm 4b is connected to the inner frame 2b via the dampers 5c and 5d.
The diaphragm 4c is connected to the inner frame 2b via dampers 5e and 5f.
d is connected to the inner frame 2b via the dampers 5g and 5h.

The inner frame 2b includes dampers 6a to 6b
Through the outer frame 2a. The outer frame 2a is fixed to a fixing member (not shown) of the piezoelectric speaker 1a.

Dampers 5a-5h and dampers 6a-6d
Are called "butterfly dampers" because of their shape.

The dampers 5a and 5b support the diaphragm 4a so that the diaphragm 4a can linearly oscillate. Here, in this specification, "the diaphragm 4a can linearly oscillate."
Means that "the surface of the diaphragm 4a and the reference surface keep substantially parallel to each other, and the diaphragm 4a vibrates in a direction substantially perpendicular to the reference surface". Define. The same definition applies to diaphragms 4b-4c and other diaphragms of the piezoelectric speaker of the present invention. For example,
The outer frame 2a is on the same plane as the paper of FIG. 1 (reference plane)
Is assumed to be fixed to In this case, the diaphragm 4a
Is supported so that the plane of the diaphragm 4a and the plane of FIG. 1 are kept substantially parallel, and the diaphragm 4a vibrates in a direction substantially perpendicular to the plane of FIG. You.

Similarly, the dampers 5c and 5d are connected to the diaphragm 4b
Supports the diaphragm 4b so that the amplitude becomes linear.
The dampers 5e and 5f support the diaphragm 4c so that the diaphragm 4c can linearly oscillate, and the dampers 5g and 5h
Diaphragm 4d so that diaphragm 4d can linearly oscillate.
I support.

The dampers 6a to 6d are arranged so that the diaphragms 4a to 4d can simultaneously and linearly oscillate.
I support.

The piezoelectric speaker 1a has an edge 7a formed to prevent air from leaking from the gap between the diaphragms 4a to 4d and the inner frame 2b, and air from the gap between the inner frame 2b and the outer frame 2a. And an edge 7b formed to prevent leakage. If air leaks from the gap between the diaphragms 4a to 4d and the inner frame 2b or from the gap between the inner frame 2b and the outer frame 2a, opposite-phase sounds generated before and after the diaphragms 4a to 4d interfere with each other. This lowers the sound pressure. The edges 7a and 7b are formed so as to prevent such air leakage, thereby preventing a decrease in sound pressure in a low frequency band where characteristic deterioration is remarkable.
As a result, according to the piezoelectric speaker 1a, it is possible to reproduce a sound in a lower frequency band as compared with the conventional piezoelectric speaker.

Further, the edges 7a and 7b are connected to the diaphragm 4a
4d function as a part of a supporting member. By supporting the periphery of the diaphragms 4a to 4d by the edges 7a and 7b, the amplitude movement of the diaphragms 4a to 4d is facilitated. If the edges 7a and 7b do not function as supporting members for the diaphragms 4a to 4d and only the dampers 5a to 5h and 6a to 6d function as supporting members for the diaphragms 4a to 4d, the diaphragms 4a to 4d Is more likely to run in an appropriate direction in a specific frequency band. As a result, unnecessary resonance is likely to occur.

FIG. 2A shows an example in which the edges 8a and 7b are formed by attaching a sheet 8 to the surface opposite to the surfaces of the vibration plates 4a to 4d on which the piezoelectric elements 3 are arranged.

The material of the sheet 8 has no air permeability,
Further, a material having elasticity is preferable. Sheet 8
Is, for example, a thin film of rubber having elasticity.
Alternatively, the sheet 8 may be formed by impregnating or coating a woven or nonwoven fabric having elasticity with a resin having rubber elasticity to perform sealing.

Examples of the elastic rubber thin film include styrene-butadiene rubber (SBR), butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), and ethylene-propylene rubber (EP).
M), ethylene-propylene-diene rubber (EPDM)
Or a rubber-based polymer resin film made of a modified material thereof.

As a material of the woven or nonwoven fabric, for example, polyurethane fibers can be used.

Further, by using an elastic polymer material having a high internal loss as the material of the sheet 8, the diaphragms 4a to 4a
The unnecessary resonance of 4d can be suppressed.

FIG. 2B shows an example in which the gap 7 between the diaphragms 4a to 4d and the inner frame 2b is filled with resin to form the edge 7a instead of using the sheet 8. The edge 7b can be formed by a similar method.

For example, the edge 7a is formed by etching or punching a metal plate to form the diaphragm 4a.
4d, the dampers 5a to 5h, and the inner frame 2b are formed, and then a solution of a polymer resin having flexibility (rubber elasticity) after curing is applied to the metal plate. The cured polymer resin 9 is held in the gap between the diaphragms 4a to 4d and the inner frame 2b, as shown in FIG. 2B.

As a method of forming the edge 7a, a capillary phenomenon caused by the surface tension of a liquid polymer resin is used.
Any method of retaining the polymer resin in the voids can be used. For example, dipping, spin coating,
The edge 7a can be formed by any method such as brush coating and spray coating. Therefore, there is an advantage that the degree of freedom in selecting a method of forming the edge 7a is high.

The polymer resin 9 is used not only for sealing air but also for removing unnecessary resonance of the dampers 5a to 5h and the vibration plates 4a to 4d. Accordingly, the polymer resin 9 is preferably a material having a high internal loss and having a certain degree of flexibility even after curing. In order to design a speaker that emphasizes the reproduction of sound in a low frequency band, for example, the elastic modulus of the polymer resin 9 is 5.0 × 10 ⁴
(N / cm ² ) or less. The reason is that the elastic modulus of the polymer resin 9 is 5.0 × 10 ⁴ (N / c
If it is higher than m ² ), it becomes difficult to obtain the amplitudes of the diaphragms 4a to 4d, and the lowest resonance frequency (f ₀ ) shifts to a higher frequency band. In addition, the polymer resin 9
Is preferably 0.05 or more. The reason is that when the internal loss of the polymer resin 9 is smaller than 0.05, the characteristic that caused the peak dip with high sharpness tends to appear in the acoustic characteristic, and the flatness of the sound pressure is easily impaired. It is.

The polymer resin 9 is desirably a material that can be used at room temperature. In particular,
It is desirable that the material can be used at 100 ° C. or lower. The reason for this is to prevent the piezoelectric element from being depolarized due to the curing temperature, since the step of forming the edge is after the step of forming the piezoelectric element. As the polymer resin 9, various types of resins having different curing conditions can be used. For example, as the polymer resin 9, it is possible to use a solvent volatile curing type, a mixed reaction curing type of two or more liquids, or a low temperature reaction type resin.

As described above, in the piezoelectric speaker 1a, the diaphragms 4a to 4d and the dampers 5a to 5h, 6a to 6d
And the edges 7a and 7b are formed on the same plane. Thereby, the thickness of the piezoelectric speaker 1a can be reduced. As a result, a thin type piezoelectric speaker can be realized.

A method of forming an edge using a resin (FIG. 2)
According to B), a thinner type piezoelectric speaker can be provided by the thickness of the sheet as compared with the method of forming an edge using a sheet (FIG. 2A).

In both the method of forming an edge using a sheet (FIG. 2A) and the method of forming an edge using a resin (FIG. 2B), the method has a high internal loss and has rubber elasticity. The resin is applied to the entire surface or a part of the surfaces of the diaphragms 4a to 4d so that
Unwanted resonances a to 4d can be effectively removed.
In this case, the internal loss of the resin is desirably 0.05 or more for the same reason as described above.

In particular, in the method of forming an edge using a resin (FIG. 2B), the resin used for forming the edge and the resin formed on the entire or partial surface of diaphragms 4a to 4d are used. By using a common resin for
The step of applying these resins using dipping, spin coating, or the like can be shared. This simplifies the manufacturing process of the piezoelectric speaker 1a.

By using a water-resistant material as such a resin material, the piezoelectric vibrating plates 4a to 4d are hardly corroded even in a high humidity condition or in a so-called water environment such as underwater. The speaker 1a can be realized. Alternatively, a material having environmental resistance such as moisture resistance, solvent resistance, heat resistance, and oxidation resistant gas may be used as the resin material. As described above, the vibration plates 4a to 4d and the piezoelectric
, It is possible to improve the environmental resistance of the entire piezoelectric speaker 1a.

FIGS. 3A and 3B show the structures of the piezoelectric speakers 1b and 1c according to the embodiment of the present invention.

Each of the piezoelectric speakers 1 b and 1 c has a single diaphragm 14 instead of the diaphragms 4 a to 4 d shown in FIG. 1 and a piezoelectric element 13 that transmits vibration to the diaphragm 14.

The diaphragm 14 is connected to the frame 12 via dampers 16a to 16d. Dampers 16a-1
6d supports the diaphragm 14 so that the diaphragm 14 can linearly oscillate.

The frame 12 has piezoelectric speakers 1b, 1c
Is fixed to a fixing member (not shown).

The positions, numbers and shapes of the dampers 16a to 16d are not limited to those shown in FIGS. 3A and 3B. The dampers 16a to 16d are
The vibration plate 14 is set so that the vibration plate 14 can linearly oscillate.
Any position, number, and shape can be adopted as long as the function of supporting is achieved.

Each of the piezoelectric speakers 1b and 1c further has an edge 17 formed to prevent air from leaking from a gap between the diaphragm 14 and the frame 12. The material and the forming method of the edge 17 are the same as those of the edge 7a described above,
7b is the same as the material and the forming method. Therefore, the description is omitted here.

FIG. 4 shows the structure of a piezoelectric speaker 1d according to an embodiment of the present invention.

The piezoelectric speaker 1d has piezoelectric elements 3a to 3d instead of the piezoelectric element 3 shown in FIG. Each of the piezoelectric elements 3a to 3d is arranged so as to transmit vibration to a corresponding one of the diaphragms 4a to 4d.

According to the piezoelectric speaker 1d, the piezoelectric element 3a
-3d simultaneously, a single diaphragm 14
As compared with the piezoelectric speakers 1b and 1c (FIGS. 3A and 3B), sound pressure in a low frequency band can be improved, and a peak dip having a large sound pressure difference can be suppressed from appearing in acoustic characteristics.

The reason that the sound pressure in the low frequency band can be improved is that the minute amplitudes in the low frequency band in each of the diaphragms 4a to 4d are combined, and the diaphragms 4a to 4d vibrate at the combined amplitude. Because.

The reason why the peak dip having a large sound pressure difference can be suppressed from appearing in the acoustic characteristics is that the diaphragms 4 a to 4 a are different from the case where a single diaphragm 14 is used.
This is because each of the diaphragms 4a to 4d is unlikely to bend because the respective areas of d are small. Diaphragms 4a to 4d
Is small, it is difficult for a peak dip having a large sound pressure difference to appear even if a resonance mode occurs in the diaphragms 4a to 4d.
Further, each of the diaphragms 4a to 4d can be more linearly amplitude-modulated. As a result, the resonance motion that occurs in the conventional piezoelectric speaker hardly occurs.

FIG. 5 shows the structure of a piezoelectric speaker 1e according to an embodiment of the present invention.

The piezoelectric speaker 1e has piezoelectric elements 3e to 3i instead of the piezoelectric element 3 shown in FIG. The piezoelectric element 3e is arranged to transmit vibration to the vibration plates 4a to 4d. Each of the piezoelectric elements 3f to 3i is arranged to transmit vibration to one of the corresponding diaphragms 4a to 4d.

As described above, by using the piezoelectric element 3e as a piezoelectric element for supplementing low-frequency reproduction and the piezoelectric elements 3f to 3i as piezoelectric elements for supplementing mid-high frequency reproduction, the structure of the piezoelectric speaker 1e is pseudo-two-way. It can be a speaker structure. As a result, the flatness of the sound pressure can be improved in a wide frequency band.

The internal loss of the edge material used for the piezoelectric speaker 1e is 0.15, and the elastic modulus of the edge material is 1.0 × 10 ⁴ (N / cm ² ).

By applying a voltage signal of 100 Hz or less to the piezoelectric element of the piezoelectric speaker of the present invention, the piezoelectric speaker can be used as a vibrator having a vibration function. Such a vibrator can be used, for example, to realize a vibration incoming call function of a mobile phone.

2. Below the acoustic characteristics of the piezoelectric speaker, the piezoelectric speaker 1a (FIG. 1) and the piezoelectric speaker 1e (FIG. 5) of the present invention are compared with a conventional piezoelectric speaker having a structure in which a metal plate is sandwiched between resin foams (FIG. 22). Will be described.

FIG. 6 shows the acoustic characteristics of the piezoelectric speaker 1a (FIG. 1) of the present invention in a JIS box. FIG. 7 shows acoustic characteristics of the piezoelectric speaker 1e (FIG. 5) of the present invention in a JIS box. FIG. 8 shows acoustic characteristics of a conventional piezoelectric speaker (FIG. 22) in a JIS box.

In the measurement of these acoustic characteristics,
The voltage applied to the piezoelectric speaker 1a (FIG. 1), the piezoelectric speaker 1e (FIG. 5), and the conventional piezoelectric speaker (FIG. 22) are each 2 V, and the measurement distance is 0.5 m.

By comparing FIGS. 6 and 8, it can be seen that the piezoelectric speaker 1a (FIG. 1) of the present invention has a lower minimum resonance frequency than the conventional piezoelectric speaker (FIG. 22). . This makes it possible to reproduce sound in a lower frequency band.

As shown in Table 1, the lowest resonance frequency of the conventional piezoelectric speaker (FIG. 22) is 300 Hz, while the lowest resonance frequency of the piezoelectric speaker 1a (FIG. 1) of the present invention is 130 Hz. is there.

[0079]

[Table 1]

As shown in FIG. 8, in the conventional piezoelectric speaker (FIG. 22), it can be seen that the sound pressure decreases as the frequency band decreases. This proves that it is difficult to reproduce sound in a low frequency band due to the structure of the conventional piezoelectric speaker (FIG. 22).

By comparing FIG. 6 with FIG. 7, the piezoelectric speaker 1e (FIG. 5) of the present invention has a frequency of 2 kHz to 5 kHz as compared with the piezoelectric speaker 1a of the present invention (FIG. 1).
It can be seen that the sound pressure of the dip has increased in the frequency band (middle range). This is an effect of attaching each of the piezoelectric elements 3f to 3i to the corresponding one of the vibration plates 4a to 4d. Thus, the piezoelectric speaker 1e
By making the structure of FIG. 5 a pseudo two-way speaker structure, dips are complemented in the middle range. As a result, the flatness of the sound pressure in the middle range is improved.

The piezoelectric speaker 1e of the present invention (FIG. 5)
According to the graph, the sound pressure is improved by about 3 dB in the frequency band (low range) of 100 Hz to 500 Hz as compared with the piezoelectric speaker 1a (FIG. 1) of the present invention. This is an effect due to each of the piezoelectric elements 3f to 3i driving a diaphragm having a smaller area than the piezoelectric element 3e. The sound pressure reproduced in each of the piezoelectric elements 3f to 3i is synthesized, so that the sound pressure level in the low frequency range is improved.

According to the piezoelectric speaker 1e (FIG. 5) of the present invention, the sound pressure is improved in the frequency band (high frequency) of 5 to 20 kHz as compared with the piezoelectric speaker 1a of the present invention (FIG. 1). It can be seen that the peak dip is reduced. This means that each of the piezoelectric elements 3f to 3i
Because it is responsible for high-frequency reproduction, sound pressure is added, and sound is reproduced in the resonance mode of one element, and the resonance mode of multiple elements is combined, and the resonance mode is seen from the whole diaphragm Is dispersed.

The piezoelectric element, diaphragm, damper, and edge included in the piezoelectric speaker of the present invention do not necessarily have to have the above-described shape and characteristics. In controlling the acoustic characteristics, various variations of the piezoelectric speaker of the present invention can be considered.

In general, a piezoelectric speaker employs a sound reproducing mechanism based on the resonance motion of a diaphragm, so that a resonance mode is easily generated in the diaphragm. Further, since a material having a low internal loss such as a metal diaphragm or ceramics is used as a material of the piezoelectric element, when resonance occurs, a characteristic in which a peak dip having a very high sharpness appears appears in the acoustic characteristics.

In order to reduce this peak dip,
Hereinafter, the effects of various parameters on the acoustic characteristics will be considered.

[0087] 3. Physical Characteristics of Butterfly Damper and Edge Hereinafter, the relationship between the change in physical characteristics of the butterfly damper and the edge, which are support members for supporting the diaphragm, and the effect on acoustic characteristics will be described.

The piezoelectric speaker having the butterfly damper 26a having the shape shown in FIG. 9A is defined as a piezoelectric speaker 1f. The piezoelectric speaker having the butterfly damper 26b having the shape shown in FIG. 9B is defined as a piezoelectric speaker 1g. Here, the elasticity of the butterfly damper having the shape shown in FIG. 9B is higher than the elasticity of the butterfly damper having the shape shown in FIG. 9A. Therefore, the piezoelectric speaker 1
g are diaphragms 4a to 4d as compared with the piezoelectric speaker 1f.
Has a structure that hardly causes amplitude (i.e., a structure that affects the resonance modes of the diaphragms 4a to 4d).

As shown in Table 2, the internal loss of the edge material was 0.1 and the elastic modulus of the edge material was 1.
A piezoelectric speaker of 7 × 10 ⁴ (N / cm ² ) is defined as a piezoelectric speaker 1h. Further, the internal loss of the edge material is 0.2 and the elastic modulus of the edge material is 0.7 × 1.
0 ⁴ (N / cm ² )
It is defined as i.

The parameters other than the physical characteristics of the butterfly dampers of the piezoelectric speakers 1f and 1g are assumed to be equal to the parameters of the piezoelectric speaker 1e (FIG. 5). Piezoelectric speaker 1h,
It is assumed that parameters other than the physical characteristics of the edge 1i are equal to the parameters of the piezoelectric speaker 1e (FIG. 5).

[0091]

[Table 2]

FIG. 10 shows the acoustic characteristics of the piezoelectric speaker 1h in the JIS box. FIG. 11 shows acoustic characteristics of the piezoelectric speaker 1i in the JIS box. FIG. 12 shows acoustic characteristics of the piezoelectric speaker 1f in a JIS box. FIG.
Shows the acoustic characteristics of the piezoelectric speaker 1g in the JIS box.

In FIGS. 10 to 13, (A) shows sound pressure frequency characteristics, and (B) shows secondary distortion characteristics.
In measuring these acoustic characteristics, the piezoelectric speakers 1f to
The voltage applied to 1i is 3.3 V, and the measurement distance is 0.5 m.

By comparing FIG. 10 with FIG. 11,
It can be seen that the piezoelectric speaker 1i having a higher internal loss of the edge material than the piezoelectric speaker 1h contributes to the improvement of the flatness of the sound pressure and the reduction of the distortion rate.

By comparing FIG. 12 and FIG. 13,
It can be seen that the peak of the piezoelectric speaker 1g having higher elasticity of the butterfly damper shifts from the lowest resonance frequency to the middle band to a higher band than the piezoelectric speaker 1f, and the resonance mode changes.

As described above, the acoustic characteristics can be affected by changing the physical characteristics of the butterfly damper and the edge, which are the supporting members for supporting the diaphragm. This is by changing the physical properties of the support member
This is because it affects the resonance mode of the diaphragm.

Note that one or more butterfly dampers included in a single piezoelectric speaker may have a plurality of portions having different physical characteristics, and one or more edges included in a single piezoelectric speaker may have one or more edges. It may have a plurality of parts having different physical characteristics. By shifting the resonance frequencies of the plurality of diaphragms, it is possible to reduce the peak dip.

[0098] 4. Acoustic Characteristics of Speaker System FIG. 14A shows an appearance of the speaker system 140. The speaker system 140 includes a speaker box 142,
Piezoelectric speaker 1f fixed to speaker box 142
To 1i. The piezoelectric speakers 1f to 1i are two-dimensionally arranged.

The above 3. As described above, the physical characteristics of the supporting members (butterfly dampers or edges) of the diaphragms of the piezoelectric speakers 1f to 1i are different from each other.

FIG. 14B shows the connection relationship between the piezoelectric speakers 1f to 1i in the speaker system 140. Each of the piezoelectric speakers 1f to 1i is electrically connected to a positive wiring 144 and a negative wiring 146. Thereby, the piezoelectric speakers 1f to 1i can be driven simultaneously.

FIG. 15 shows the JI of the speaker system 140 when the piezoelectric speakers 1f to 1i are simultaneously driven.
Fig. 6 shows acoustic characteristics of the S box.

In FIG. 15, (A) shows sound pressure frequency characteristics, and (B) shows secondary distortion characteristics. In the measurement of the acoustic characteristics, the voltage applied to the piezoelectric speakers 1f to 1i is 3.3 V, and the measurement distance is 0.5 m.

By comparing FIG. 15 with each of FIGS. 10 to 13, it can be seen that the flatness of the sound pressure is improved by combining the piezoelectric speakers 1f to 1i. This is because the piezoelectric speakers 1f to 1i complement the peak dip with each other.

As described above, by simultaneously driving a plurality of piezoelectric speakers in which the physical characteristics of the support member are intentionally changed so as to complement the peak dips, a speaker system having excellent sound pressure flatness can be obtained. Can be realized.

[0105] 5. Weight balance of the diaphragm will be explained the relationship between the influence of the weight balance and the acoustic characteristics of the diaphragm.

The above 3. A piezoelectric speaker using the diaphragms 4a to 4d as shown in FIG. 16 instead of the diaphragm of the piezoelectric speaker 1h described above is defined as a piezoelectric speaker 1j. Here, the weight of the diaphragms 4a to 4d shown in FIG. 16 is such that the weight ratio of the diaphragms 4a, 4b, 4c, and 4d is 1: 2: 3: 4.
Is set in advance so that

The weight balance of the diaphragms 4a to 4d can be adjusted by, for example, applying different amounts of polymer resin to the diaphragms 4a to 4d, thereby forming Obtained by forming a polymer resin. The polymer resin formed on the diaphragms 4a to 4d provides an advantage that the flatness of sound pressure is improved by a damping effect of the polymer resin.

Alternatively, the above-mentioned weight balance of the diaphragms 4a to 4d may be obtained by applying polymer resins having different densities to the diaphragms 4a to 4d.

As the polymer resin, the same resin as that used for forming the edge can be used.

FIG. 17 shows the acoustic characteristics of the piezoelectric speaker 1j in the JIS box.

In FIG. 17, (A) shows the sound pressure frequency characteristic, and (B) shows the secondary distortion characteristic. In the measurement of the acoustic characteristics, the voltage applied to the piezoelectric speaker 1j is 3.3 V, and the measurement distance is 0.5 m.

By comparing FIG. 17 with FIG.
It can be seen that the piezoelectric speaker 1j contributes to the suppression of the resonance peak and the improvement of the flatness of the sound pressure more than the piezoelectric speaker 1h. This is because the resonance modes of the diaphragms 4a to 4d are shifted by making the weights of the diaphragms 4a to 4d different.

As described above, by changing the weight balance of the diaphragm, it is possible to influence the acoustic characteristics.

The weight ratio of the vibrating plates 4a, 4b, 4c, and 4d is reduced by a half etching process of the metal vibrating plate.
By making the thicknesses of the diaphragms 4a to 4d different so that the ratio becomes 2: 3: 4, the same effect as that described above can be obtained. This is because the resonance modes of the vibration plates 4a to 4d are shifted.

Note that the above 3. By combining the change in the physical property of the edge or the change in the physical property of the butterfly damper with the change in the weight balance of the diaphragm, it is possible to influence the acoustic properties.

[0116] 6. Piezoelectric element FIG. 18 shows the structure of a piezoelectric speaker 1k according to an embodiment of the present invention. A piezoelectric element 180 is arranged on diaphragms 4a to 4d of piezoelectric speaker 1k. Piezoelectric speaker 1k
Parameters other than the piezoelectric element 180 of the piezoelectric speaker 1
e (FIG. 5).

The piezoelectric element 180 has a shape in which a plurality of piezoelectric elements 3e to 3i shown in FIG. 5 are partially connected. Thereby, compared with the piezoelectric speaker 1e (FIG. 5), the step of electrically connecting the piezoelectric elements 3e to 3i by wiring can be omitted.

Although not shown in FIG. 18, a piezoelectric element having a diameter of 24 mm is affixed to the back surfaces of the diaphragms 4a to 4d, similarly to the piezoelectric speaker 1e (FIG. 5).

FIG. 19 shows the acoustic characteristics of the piezoelectric speaker 1k in the JIS box.

In FIG. 19, (A) shows sound pressure frequency characteristics, and (B) shows secondary distortion characteristics. In the measurement of the acoustic characteristics, it is assumed that the voltage applied to the piezoelectric speaker 1k is 3.3V.

As shown in FIG. 19, the piezoelectric speaker 1
According to k, sound in a lower frequency band can be reproduced.

The shape of the diaphragm of the piezoelectric speaker 1k is shown in FIG.
Is defined as the piezoelectric speaker 1m. However, the diameter φ of the piezoelectric element disposed on the back surface of the diaphragm as a bimorph was 32 mm. The piezoelectric element is arranged not at the center of the diaphragm but at a position shifted downward from the center of the diaphragm to immediately before the damper. Thereby, the resonance mode changes.

The edge material used for the piezoelectric speaker 1m is the same as the edge material used for the piezoelectric speaker 1e (FIG. 5). That is, the internal loss of the edge material is 0.15, and the elastic modulus of the edge material is 1.0 × 1.
0 ⁴ (N / cm ² ).

FIG. 23 shows the acoustic characteristics of the piezoelectric speaker 1m in the JIS box.

In FIG. 23, (A) shows sound pressure frequency characteristics, and (B) shows secondary distortion characteristics. In the measurement of the acoustic characteristics, the voltage applied to the piezoelectric speaker 1 m is 7.0 V, and the measurement distance is 0.5 m.

In the piezoelectric speaker 1m, the piezoelectric element is arranged so as to be shifted from the center of the diaphragm. Thereby, the resonance mode changes. As a result, as shown in FIG. 23, in the above-described piezoelectric speakers 1a to 1k, 1 kHz to 2 k
It becomes possible to reduce the peak dip occurring in the frequency band of Hz.

The diaphragm of the piezoelectric speaker 1m has an internal loss of 0.4 and an elastic modulus of 0.5 × 10 ⁴ (N / c
m ² ) coated with a rubber-based polymer resin is defined as a piezoelectric speaker 1n.

FIG. 24 shows the acoustic characteristics of the piezoelectric speaker 1n in the JIS box.

In FIG. 24, (A) shows a sound pressure frequency characteristic, and (B) shows a secondary distortion characteristic. In the measurement of the acoustic characteristics, the voltage applied to the piezoelectric speaker 1n is 7.0 V, and the measurement distance is 0.5 m.

As shown in FIG. 24, the piezoelectric speaker 1
According to n, the distortion can be effectively reduced by applying a material having a high internal loss to the diaphragm,
The flatness of sound pressure can be improved.

[0131] 7. High used to form the edge
UV irradiation for 60 seconds at a distance of 2.0 cm using a 70 W low-pressure ultraviolet lamp on the surface of the metal diaphragm processed into a predetermined shape by adhesive etching or punching of a molecular resin.
Was irradiated. The ultraviolet UV used here is generated using a low-pressure mercury lamp as a light source, and the wavelength of 80% of the emitted ultraviolet UV is 253.7.
and the wavelength of 6% ultraviolet light UV is 184.9 nm.
Met.

By the energy of the irradiated ultraviolet rays UV,
Cleaning (decomposition of impurities) of the surface of the metal diaphragm is performed.
In addition, active oxygen, which is a decomposition product of ozone generated by the energy of ultraviolet rays UV, causes-
A hydrophilic functional group such as OH or -COOH can be provided. As a result, polarity can be given to the metal diaphragm. With this effect, the wettability of the metal diaphragm with respect to the polymer resin used to form the edge can be improved, and the adhesiveness between the polymer resin and the metal diaphragm can be improved.

Even when the surface of the metal diaphragm is irradiated with plasma, corona, or the like, the metal diaphragm is modified for the same reason as described above. Thereby, the adhesiveness between the polymer resin and the metal diaphragm can be improved.

Since the piezoelectric material used here is depolarized in an environment of 100 ° C., when a resin that requires heat fusion is used, the temperature of the diaphragm and the polymer resin material at a lower temperature becomes lower. Adhesion is required.

[0135] 8. Hereinafter, a method of manufacturing the piezoelectric speaker 1e (FIG. 5) will be described as a representative example of the method of manufacturing the piezoelectric speaker of the present invention. The same applies to the method of manufacturing the other piezoelectric speakers 1a to 1d and 1f to 1j. The method of manufacturing the piezoelectric speaker 1e (FIG. 5) includes a step of processing a plate, a step of arranging a piezoelectric element, a step of forming an edge, and a step of forming wiring.

Hereinafter, each step will be described in detail with reference to FIGS. 20A to 20N.

8.1 Step of Processing Plate In this step, the outer frame 2a, the inner frame 2b, the diaphragms 4a to 4d, and the dampers 5a to 5h and 6a to 6d are formed by processing the plate.

The dampers 5a and 5b support the diaphragm 4a and are formed such that the diaphragm 4a can linearly oscillate. Similarly, the dampers 5c and 5d are connected to the diaphragm 4b
And the diaphragm 4b is formed so as to be capable of linearly oscillating, and the dampers 5e and 5f are formed so as to support the diaphragm 4c and to be capable of linearly oscillating the diaphragm 4c. , Dampers 5g and 5h support the diaphragm 4d and are formed so that the diaphragm 4d can linearly oscillate.

For example, the members described above can be formed by etching or punching the metal plate 200. As the metal plate 200, for example,
A 42 alloy metal plate having a thickness of 100 μm can be used. Instead of the metal plate 200, a conductive plastic or a plastic plate having electrodes formed at predetermined locations may be used.

FIG. 20A shows the metal plate 200 before processing. FIG. 20B shows the metal plate 200 after processing. In addition,
In FIG. 20B, reference numeral 10a denotes diaphragms 4a to 4d.
And a gap between the inner frame 2b and the inner frame 2b.
0b indicates a gap between the inner frame 2b and the outer frame 2a.

As shown in FIG. 21, punching of a position corresponding to a position where the piezoelectric element 3e is to be arranged in the subsequent step (indicated by a broken line in FIG. 21) may be omitted.

8.2 Step of Placing Piezoelectric Element In this step, two kinds of piezoelectric elements are used.

The piezoelectric element 3e has a thickness of 50 μm and a diameter of φ2.
4 mm PZT (lead zirconate titanate) piezoelectric element. Electrodes are formed by conductive paste on both surfaces of the piezoelectric element 3e.

Each of the piezoelectric elements 3f to 3i has a diameter φ
10 mm PZT (lead zirconate titanate) piezoelectric element. Electrodes are formed of conductive paste on both surfaces of each of the piezoelectric elements 3f to 3i.

The piezoelectric element 3e is placed at the position (X) shown in FIG. 20C by using, for example, an acrylic adhesive.
Affixed. The piezoelectric elements 3e are provided on both sides of the metal plate (that is, the vibrating plates 4a to 4d) so as to form a bimorph structure.
Is formed). Thus, the piezoelectric element 3e is arranged so as to transmit vibration to the vibration plates 4a to 4d.

Each of the piezoelectric elements 3f to 3i is shown in FIG.
At the position (Y) shown in C, for example, it is stuck using an acrylic adhesive. Each of the piezoelectric elements 3f to 3i is formed on one side of the metal plate (that is, only on the upper surfaces of the vibration plates 4a to 4d) so as to form a monomorph structure. In this way, each of the piezoelectric elements 3f to 3i is arranged to transmit vibration to one of the corresponding vibration plates 4a to 4d.

It should be noted that the polarity of the piezoelectric element 3e and the piezoelectric element 3e
The piezoelectric elements 3e and 3f to 3i are arranged such that the polarities of f to 3i are the same when viewed from above the diaphragms 4a to 4d.

8.3 Step of Forming Edge In this step, diaphragms 4a to 4d and inner frame 2b
An edge 7a is formed in the gap 10a between the inner frame 2b and the edge 7b in the gap 10b between the inner frame 2b and the outer frame 2a (FIG. 20D). Edges 7a, 7
b is formed so as to have a function of preventing air from leaking from the gaps 10a and 10b and a function of supporting the diaphragms 4a to 4d.

The edges 7a and 7b are made of, for example, styrene-
The voids 10a and 10b are filled with a solution of a polymer resin of butadiene rubber (SBR) using a squeegee, and the solution of the polymer resin is filled with the void using the surface tension (capillary phenomenon) of the solution of the polymer resin. While being held at 10a and 10b, it can be dried and cured at room temperature for 30 minutes, and then left to stand in a constant temperature bath at 50 ° C. for 1 hour to be further dried and cured.

For example, by changing the compounding ratio of the SBR rubber, it is possible to form edges having different physical characteristics (internal loss and elastic modulus).

When a solution of the polymer resin that cures in a temperature range (100 ° C. to normal temperature) where the piezoelectric element is not depolarized is used, drying is performed to speed up the edge forming step. Can be. In addition, depending on the type of the solution of the polymer resin, by performing a crosslinking reaction, the edge forming step can be speeded up.

For the purpose of simplifying the process, a solution of a polymer resin may be applied to the gaps 10a and 10b by using a dipping method or a spin coating method.
In this case, it is necessary to use a mask to prevent the electrodes of the piezoelectric element from being completely covered with the polymer resin. This is because if the electrodes of the piezoelectric element are completely covered with the polymer resin, the electrodes will be insulated.

The above 1 .. As described above, the edges 7a and 7b can also be formed by attaching a sheet impregnated with a polymer resin to the back surfaces of the vibration plates 4a to 4d.

8.4 Step of Forming Wiring For example, an insulating resin is applied by using a screen printing method,
After drying at room temperature for 30 minutes, the insulating film 2 is dried in a thermostat at 50 ° C. for 1 hour to prevent the piezoelectric elements 3 e to 3 i and the metal vibration plates 4 a to 4 d from being short-circuited.
8 are formed (FIG. 20E).

Here, as the insulating resin, the edge 7a,
The same resin as that used to form 7b can be used.

The main purpose of the insulating film 28 is to make the piezoelectric elements 3e to
3i is insulated from the metal diaphragms 4a to 4d.
Therefore, the insulating film 28 need only be a film that does not have pinholes and sufficiently withstands insulation, and the shape and amount of the insulating film 28 need not be a specific shape or a specific amount. However, as the material of the insulating film 28, a material having high internal loss and flexibility is desirable.

Next, a wiring 29 for electrically connecting the piezoelectric element 3e and each of the piezoelectric elements 3f to 3i is formed by applying a conductive paste using, for example, a screen printing method (FIG. 20F). .

Similarly, an insulating film 38a is formed at a predetermined position on the surface of diaphragms 4a to 4d (FIG. 20G), and an insulating film 38b is formed at a predetermined position on the back surface of diaphragms 4a to 4d (FIG. 20G). (FIG. 20H). Wiring 4 on insulating film 38a
9a is formed (FIG. 20I), and a wiring 49b is formed on the insulating film 38b (FIG. 20J).

Thereafter, the external terminal 51 is inserted so as to sandwich the wiring 49a and the wiring 49b (FIG. 20K).
FIG. 20L shows a cross section taken along line LL ′ shown in FIG. 20K.

Here, the application of the insulating resin is performed by using a mask 68a.
(FIG. 20M) and the formation of the edges 7a and 7b using the mask 68b (FIG. 20N) may be performed simultaneously.

[0161] The conductive paste used here is of a solvent-evaporating type, and is of a type in which conductive performance can be obtained at a temperature not higher than the temperature at which the piezoelectric element is depolarized.

[0162]

According to the piezoelectric speaker of the present invention, the diaphragm is supported so that the diaphragm can linearly oscillate, so that air is prevented from leaking from the gap between the diaphragm and the frame. An edge is formed as a support member for keeping the amplitude of the diaphragm flat. This makes it possible to reproduce sound in a lower frequency band as compared with a conventional piezoelectric speaker.

According to another piezoelectric speaker of the present invention, a plurality of diaphragms are supported such that each of the plurality of diaphragms can linearly swing. Thereby, the resonance motion due to the surface shape is distributed to the plurality of diaphragms. As a result, a peak dip having a large sound pressure difference is prevented from appearing in the acoustic characteristics.

According to the method for manufacturing a piezoelectric speaker of the present invention, it is possible to provide a piezoelectric speaker having the above-described structure.

By combining a plurality of piezoelectric speakers having the above-described structure, a speaker system having a sufficiently flat sound pressure level can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view showing a structure of a piezoelectric speaker 1a according to an embodiment of the present invention.

FIG. 2A is a diagram for explaining an example in which edges 7a and 7b are formed by attaching a sheet 8 to diaphragms 4a to 4d.

FIG. 2B is a view for explaining an example in which an edge 7a is formed by filling a gap between the diaphragms 4a to 4d and the inner frame 2b with a resin.

FIG. 3A is a plan view showing a structure of a piezoelectric speaker 1b according to the embodiment of the present invention.

FIG. 3B is a plan view showing the structure of the piezoelectric speaker 1c according to the embodiment of the present invention.

FIG. 4 is a plan view showing a structure of a piezoelectric speaker 1d according to the embodiment of the present invention.

FIG. 5 is a plan view showing a structure of a piezoelectric speaker 1e according to the embodiment of the present invention.

FIG. 6 is a diagram showing acoustic characteristics of the piezoelectric speaker 1a (FIG. 1) in a JIS box.

FIG. 7 is a diagram showing acoustic characteristics of the piezoelectric speaker 1e (FIG. 5) in a JIS box.

8 is a diagram showing acoustic characteristics of a conventional piezoelectric speaker (FIG. 22) in a JIS box.

FIG. 9A is a diagram showing a shape of a butterfly damper used in the piezoelectric speaker 1f.

FIG. 9B is a diagram showing a shape of a butterfly damper used in the piezoelectric speaker 1g.

FIG. 10 is a diagram showing acoustic characteristics of a piezoelectric speaker 1h in a JIS box.

FIG. 11 is a diagram illustrating acoustic characteristics of a piezoelectric speaker 1i in a JIS box.

FIG. 12 is a diagram illustrating acoustic characteristics of a piezoelectric speaker 1f in a JIS box.

FIG. 13 is a diagram showing acoustic characteristics of a piezoelectric speaker 1g in a JIS box.

14A is a diagram showing an appearance of a speaker system 140. FIG.

14B is a diagram showing a connection relationship between piezoelectric speakers 1f to 1i in the speaker system 140. FIG.

FIG. 15 is a diagram showing acoustic characteristics of a speaker system 140 in a JIS box.

FIG. 16 is a view showing diaphragms 4a to 4d used in the piezoelectric speaker 1j.

FIG. 17 is a diagram showing acoustic characteristics of a piezoelectric speaker 1j in a JIS box.

FIG. 18 is a plan view showing a structure of a piezoelectric speaker 1k according to an embodiment of the present invention.

FIG. 19 is a diagram showing acoustic characteristics of a piezoelectric speaker 1k in a JIS box.

FIG. 20A is a diagram showing a shape of a metal plate 200 before processing.

FIG. 20B is a diagram showing the shape of the metal plate 200 after processing.

FIG. 20C is a diagram showing a state where the piezoelectric elements 3e to 3i are arranged.

FIG. 20D is a diagram showing a state where edges 7a and 7b are formed.

FIG. 20E is a diagram showing a state in which the insulating coating 28 has been formed.

FIG. 20F is a diagram showing a state where the wiring 29 is formed.

FIG. 20G is a diagram showing a state where an insulating film 38a is formed.

FIG. 20H is a diagram showing a state where an insulating film 38a is formed.

FIG. 20I is a view showing a state in which a wiring 49a is formed.

FIG. 20J is a view showing a state in which a wiring 49b is formed.

20K is a diagram showing a state where the external terminal 51 is inserted. FIG.

FIG. 20L is a drawing showing a cross section along the line LL ′ shown in FIG. 20K;

FIG. 20M is a diagram showing a shape of a mask 68a.

FIG. 20N is a diagram showing a shape of a mask 68b.

FIG. 21 is a diagram showing a shape of a metal plate 200 after processing.

FIG. 22 is a diagram showing a structure of a conventional piezoelectric speaker 220.

FIG. 23 is a diagram showing acoustic characteristics of a piezoelectric speaker 1m in a JIS box.

FIG. 24 is a diagram showing acoustic characteristics of a piezoelectric speaker 1n in a JIS box.

[Explanation of symbols]

 1a to 1k, 1m to 1n Piezoelectric speaker 2a Outer frame 2b Inner frame 3, 3a to 3i Piezoelectric element 4a to 4d Diaphragm 5a to 5h Damper 6a to 6d Damper 7a, 7b Edge 8 Sheet 9 Polymer resin 12 Frame 13 Piezoelectric element 14 diaphragm 16a-16d damper 17 edge 140 speaker system

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-271096 (JP, A) JP-A-63-257400 (JP, A) JP-A-60-177798 (JP, A) JP-A 53-257 76823 (JP, A) Fully open 1983-87642 (JP, U) Fully open, 58-82091 (JP, U) Fully open, 58-100000 (JP, U) Fully open, 55-137199 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) H04R 17/00 H04R 1/22 310 H04R 7/06 H04R 31/00

Claims (21)

(57) [Claims] 1. A frame, a vibration plate, a piezoelectric element arranged on the vibration plate, and connected to the frame and the vibration plate, and the vibration is performed so that the vibration plate can linearly oscillate. A damper for supporting a plate, an edge formed so as to fill a gap between the diaphragm, the damper, and the frame, the diaphragm;
A piezoelectric speaker, wherein the damper and the edge are formed on the same plane. 2. A frame, a plurality of diaphragms, at least one piezoelectric element arranged on the plurality of diaphragms, and the plurality of diaphragms connected to the frame and the plurality of diaphragms. A plurality of dampers supporting the plurality of diaphragms so that each of the plurality of diaphragms can linearly swing, and an edge formed so as to fill a gap between the plurality of diaphragms, the plurality of dampers, and the frame. With
A piezoelectric speaker, wherein the plurality of diaphragms, the plurality of dampers, and the edge are formed on the same plane. 3. The at least one piezoelectric element comprises a first piezoelectric element.
And a plurality of second piezoelectric elements, wherein the first
3. The piezoelectric element according to claim 2, wherein vibration is transmitted to the plurality of vibration plates, and each of the plurality of second piezoelectric elements transmits vibration to a corresponding one of the plurality of vibration plates. 4. Piezoelectric speaker. 4. The piezoelectric speaker according to claim 2, wherein a resin is formed on at least a part of a surface of each of the plurality of diaphragms. 5. The piezoelectric speaker according to claim 4, wherein a common resin is used as the resin and a resin used to form the edge. 6. The piezoelectric speaker according to claim 2, wherein the plurality of dampers include a plurality of portions having different physical characteristics. 7. The piezoelectric speaker according to claim 1, wherein the edge includes a plurality of portions having different physical characteristics. 8. The piezoelectric speaker according to claim 2, wherein the plurality of diaphragms have different weights. 9. The piezoelectric speaker according to claim 8, wherein resins having different thicknesses are formed on the plurality of diaphragms. 10. The piezoelectric speaker according to claim 8, wherein the plurality of diaphragms have different thicknesses. 11. By processing a plate, it is connected to a frame, a plurality of diaphragms, and the frame and the plurality of diaphragms, and each of the plurality of diaphragms can linearly swing. Forming a plurality of dampers supporting the plurality of diaphragms such that the plurality of diaphragms and the plurality of dampers are on the same plane; and forming at least one piezoelectric element on the plurality of diaphragms A method of manufacturing a piezoelectric speaker, comprising: arranging an element; and forming, on the same plane, an edge that fills a gap between the plurality of diaphragms, the plurality of dampers, and the frame. 12. The method according to claim 11, wherein the edge is formed by attaching a sheet to the plurality of diaphragms. 13. The method according to claim 12, wherein the sheet is a thin film of rubber having elasticity. 14. The method of manufacturing a piezoelectric speaker according to claim 12, wherein the sheet is made by impregnating or coating a woven or nonwoven fabric having elasticity with a resin having rubbery elasticity. 15. The edge is formed by holding the polymer resin in the gap between the plurality of diaphragms and the frame using a capillary phenomenon caused by surface tension of a liquid polymer resin. The method of manufacturing a piezoelectric speaker according to claim 11, wherein: 16. The polymer resin is a solvent volatile curing type,
The method of manufacturing a piezoelectric speaker according to claim 15, wherein the resin is one of a two-part or more mixed reaction curing type resin and a low temperature reaction type resin. 17. The method according to claim 15, wherein the polymer resin is held in the gap using a dipping method or a spin coating method. 18. The method for manufacturing a piezoelectric speaker according to claim 15, further comprising, before the step of forming the edge, a step of improving adhesion between the plurality of diaphragms and the polymer resin. 19. The method according to claim 11, further comprising a step of electrically connecting the at least one piezoelectric element. 20. A speaker system including a plurality of piezoelectric speakers, wherein each of the plurality of piezoelectric speakers is the piezoelectric speaker according to claim 4. 21. The speaker system according to claim 20, wherein the plurality of piezoelectric speakers have different acoustic characteristics so as to complement peak dips.