JP2016213550A - Speaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a speaker capable of suppressing deterioration of sound quality.SOLUTION: The speaker according to an aspect of an embodiment includes a piezoelectric actuator and a plurality of diaphragms. The piezoelectric actuator expands and contracts in accordance with a given voltage. The plurality of diaphragms generate sound by vibrating in resonance frequencies different from each other in accordance with expansion and contraction of the piezoelectric actuator.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to a speaker.

  Conventionally, a piezoelectric speaker using a piezoelectric element (piezo element) is known. In such a speaker, by attaching a piezoelectric element to the diaphragm, the diaphragm is resonated to increase the sound pressure (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 4-119200

  However, if the sound pressure is increased due to resonance of the diaphragm, resonance does not occur at all frequencies. Therefore, if the sound pressure is increased using the sound pressure, the peak dip of the sound pressure frequency characteristic increases and the sound quality deteriorates. There is a problem.

  The present invention has been made in view of the above, and an object of the present invention is to provide a speaker capable of suppressing deterioration in sound quality.

  In order to solve the above problems and achieve the object, a speaker of the present invention includes a piezoelectric actuator and a plurality of diaphragms. The piezoelectric actuator expands and contracts according to the applied voltage. The plurality of diaphragms vibrate at different resonance frequencies according to the expansion and contraction of the piezoelectric actuator and generate sound.

  According to the present invention, deterioration of sound quality can be suppressed.

FIG. 1A is a perspective view illustrating a configuration example of a speaker according to the first embodiment. FIG. 1B is a top view illustrating a configuration example of the speaker according to the first embodiment. FIG. 1C is a cross-sectional view of the speaker taken along line X1 in FIG. 1B. FIG. 2A is a diagram illustrating an example of sound pressure frequency characteristics when a plurality of diaphragms are vibrated, respectively. FIG. 2B is a diagram illustrating an example of a sound pressure frequency characteristic of the speaker according to the first embodiment. FIG. 3A is a top view illustrating a configuration example of the speaker according to the second embodiment. FIG. 3B is a cross-sectional view of the speaker taken along line X1 in FIG. 3A. FIG. 4A is a top view illustrating a configuration example of a speaker according to a third embodiment. FIG. 4B is a side view illustrating a configuration example of the speaker according to the third embodiment. FIG. 5A is a top view illustrating a configuration example of a speaker according to the first modification. FIG. 5B is a side view illustrating a configuration example of the speaker according to the first modification. FIG. 6A is a top view illustrating a configuration example of a speaker according to a fourth embodiment. 6B is a cross-sectional view of the speaker taken along line X1 in FIG. 6A. FIG. 7A is a top view illustrating a configuration example of a speaker according to a fifth embodiment. FIG. 7B is a side view illustrating a configuration example of the speaker according to the fifth embodiment. FIG. 8A is a top view illustrating a configuration example of a speaker according to a sixth embodiment. FIG. 8B is a side view illustrating a configuration example of the speaker according to the sixth embodiment. FIG. 9A is a top view illustrating a configuration example of a speaker according to a seventh embodiment. FIG. 9B is a cross-sectional view of the speaker taken along line X1 in FIG. 9A. FIG. 10A is an enlarged view of a region R1 in FIG. 9A. FIG. 10B is a view of the region R1 in FIG. 9A viewed from the X-axis direction. FIG. 11 is a diagram illustrating a recess according to the second modification. FIG. 12 is a cross-sectional view illustrating a configuration example of a speaker according to the third modification. FIG. 13A is a top view illustrating a configuration example of a speaker according to an eighth embodiment. FIG. 13B is a side view illustrating a configuration example of the speaker according to the eighth embodiment. FIG. 14 is a top view illustrating a configuration example of a speaker according to the fourth modification.

  Hereinafter, embodiments of a speaker disclosed in the present application will be described in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

<1. First Embodiment>
FIG. 1 is a diagram illustrating a configuration example of a speaker 100 according to the first embodiment. FIG. 1A is a perspective view of the speaker 100. 1B is a top view of the speaker 100, and FIG. 1C is a cross-sectional view of the speaker 100 taken along line X1 in FIG. 1B.

  FIG. 1A shows a three-dimensional orthogonal coordinate system including a Z axis with the upward direction in the drawing as a positive direction and the downward direction in the drawing as a negative direction. Such an orthogonal coordinate system may be shown in other drawings used in the following description.

  As shown in FIG. 1, the speaker 100 includes a frame 10, a plurality of diaphragms 20 </ b> A and 20 </ b> B, and a piezoelectric actuator 30.

  The diaphragms 20A and 20B are plate-like members that vibrate according to the expansion and contraction of the piezoelectric actuator 30 and generate sound. The diaphragms 20A and 20B have a substantially rectangular vibration surface. The diaphragms 20A and 20B are arranged so that the vibration surfaces are substantially on the same plane (the XY plane in FIG. 1). In the example shown in FIG. 1B, the diaphragms 20A and 20B are arranged with a gap G apart.

  The diaphragms 20A and 20B have different resonance frequencies. The diaphragms 20A and 20B are made of, for example, a metal such as aluminum, iron, or copper, a resin such as an ABS resin, an acrylic resin, or a polycarbonate, a material such as paper or wood. At this time, in order to make the resonance frequencies of the diaphragms 20A and 20B different from each other, for example, the diaphragm 20A and the diaphragm 20B may be made of different materials.

  It is desirable that the diaphragms 20A and 20B have greatly different resonance frequencies. For this reason, when one of the diaphragms 20A and 20B is a metal, the other is desirably made of a material other than metal (for example, resin). If the resonance frequencies of the diaphragms 20A and 20B are different from each other, both the diaphragms 20A and 20B may be made of metal or resin.

  Alternatively, the resonance frequencies may be different depending on the shape and size of the diaphragms 20A and 20B. In this case, the diaphragms 20A and 20B may be made of the same material (for example, aluminum). Alternatively, the resonance frequencies of the diaphragms 20A and 20B may be different from each other by adjusting the positional relationship between the diaphragms 20A and 20B and the piezoelectric actuator 30.

  The frame 10 has a substantially rectangular bottom surface 10A and a frame-shaped support wall 10B. The frame 10 is a box-shaped member having an opening on the surface facing the bottom surface 10A. The frame 10 is fixed to the placement target of the speaker 100. For example, when the arrangement target is an instrument panel in a vehicle cabin, the frame 10 is fixed to the instrument panel.

  The support wall 10B is in contact with the outer peripheral portion of the diaphragms 20A and 20B excluding the adjacent sides. Thereby, the support wall 10B supports the diaphragms 20A and 20B. As described above, the support wall 10B of the frame 10 supports the outermost peripheral portion of the region formed by the diaphragms 20A and 20B. Hereinafter, the outer peripheral portions of the diaphragms 20A and 20B that are in contact with the support wall 10B are also referred to as fixed ends, and the outer peripheral portions of the diaphragms 20A and 20B that are not in contact with the support wall 10B are also referred to as free ends.

  The piezoelectric actuator 30 expands and contracts in the longitudinal direction (X-axis direction) according to the applied voltage. For example, the piezoelectric actuator 30 shown in FIG. 1 is a monomorph type actuator composed of one piezoelectric element.

  As shown in FIG. 1C, the piezoelectric actuator 30 is provided in a space formed by the frame 10 and the diaphragms 20A and 20B. Further, as shown in FIG. 1B, the piezoelectric actuator 30 is provided at substantially the center of the region formed by the diaphragms 20A and 20B.

  The piezoelectric actuator 30 has a substantially rectangular main surface, and is arranged so that the main surface is in contact with the vibration surface of the vibration plate 20A and the vibration surface of the vibration plate 20B. Thereby, according to expansion and contraction of the piezoelectric actuator 30, both the diaphragms 20A and 20B vibrate, and sound is generated from the diaphragms 20A and 20B.

  Here, the piezoelectric actuator 30 is assumed to be a monomorph actuator, but is not limited thereto. For example, a bimorph type actuator or a stacked type actuator may be used.

  Next, the operation of the speaker 100 will be described with reference to FIG. FIG. 2A is a diagram illustrating an example of sound pressure frequency characteristics when the plurality of diaphragms 20A and 20B are respectively vibrated. FIG. 2B is a diagram illustrating an example of a sound pressure frequency characteristic of the speaker 100 according to the first embodiment. In FIG. 2, the horizontal axis represents frequency and the vertical axis represents sound pressure.

  Moreover, the solid line in FIG. 2A shows an example of the sound pressure frequency characteristic when the diaphragm 20A is vibrated, and the dotted line shows an example of the sound pressure frequency characteristic when the diaphragm 20B is vibrated. .

  For example, in the example of FIG. 2A, when the diaphragm 20A is vibrated, a dip in which the sound pressure decreases at the frequency F1 occurs, and a peak in which the sound pressure increases at the frequency F2 occurs. On the other hand, when the diaphragm 20B is vibrated, a peak in which the sound pressure increases at the frequency F1 occurs, and a dip in which the sound pressure decreases near the frequency F2 occurs.

  As shown in FIG. 2A, when the plurality of diaphragms 20A and 20B are individually vibrated, the peak dip of the sound pressure frequency characteristic is increased, and the sound quality is deteriorated. Therefore, in the speaker 100 of the present embodiment, the plurality of diaphragms 20A and 20B are vibrated by the piezoelectric actuator 30. Thereby, the peak dips of the sound pressure frequency characteristics of the diaphragms 20A and 20B are canceled out, and the sound pressure frequency characteristics of the speaker 100 become flat as shown in FIG. 2B.

  As described above, the speaker 100 according to the present embodiment can flatten the sound pressure frequency characteristics of the speaker 100 by vibrating the diaphragms 20A and 20B arranged on the same plane by the piezoelectric actuator 30. Thereby, the speaker 100 can suppress deterioration of sound quality.

  Further, in the speaker 100 according to the present embodiment, the diaphragms 20A and 20B are arranged with a gap G apart, and the outermost peripheral portion of the region formed by the diaphragms 20A and 20B is supported by the support wall 10B. As a result, the adjacent outer peripheral portions of the diaphragms 20A and 20B become free ends, and the diaphragms 20A and 20B are likely to resonate. That is, the types of resonance modes of the diaphragms 20A and 20B increase.

  For example, when the resonance frequencies of the diaphragms 20A and 20B are close, that is, when the sound pressure frequency characteristics when the diaphragms 20A and 20B are vibrated are similar, even if the diaphragms 20A and 20B are simply vibrated simultaneously, The peak dips of the sound pressure frequency characteristics may not cancel each other.

  Even in such a case, the types of resonance modes of the diaphragms 20A and 20B can be increased by setting the outer peripheral portions of the diaphragms 20A and 20B adjacent to each other as free ends as described above. Accordingly, the diaphragms 20A and 20B can be vibrated in different resonance modes, and the number of peak dips in the sound pressure frequency characteristic of the speaker 100 can be reduced. Thus, since diaphragm 20A, 20B has a free end, the sound pressure frequency characteristic of the speaker 100 can be planarized and deterioration of sound quality can be suppressed.

  In addition, although embodiment mentioned above demonstrated the case where the some diaphragm 20A, 20B was two sheets, the number of diaphragms is not restricted to this. The number of diaphragms may be two or more. Moreover, although the case where each of the diaphragms 20A and 20B is configured by one type of material has been described, each of the diaphragms 20A and 20B may be configured by combining a plurality of materials. For example, the diaphragms 20A and 20B may be configured by bonding plates made of different materials.

  In the above-described embodiment, the case where the shapes of the diaphragms 20A and 20B are rectangular has been described, but the present invention is not limited thereto. For example, the diaphragms 20A and 20B may have a shape obtained by dividing an elliptical plate into two. Further, the diaphragms 20A and 20B do not have to have the same shape and may not have the same size.

  Moreover, although embodiment mentioned above demonstrated the case where the piezoelectric actuator 30 was arrange | positioned in the approximate center of the area | region formed by diaphragm 20A, 20B, it is not restricted to this. For example, by arranging the piezoelectric actuator 30 closer to the diaphragm 20A, the area where the piezoelectric actuator 30 and the diaphragm 20A are in contact may be larger than the area where the piezoelectric actuator 30 and the diaphragm 20B are in contact. Thus, the resonance frequency of the diaphragms 20A and 20B may be made different by making the areas where the piezoelectric actuator 30 and the diaphragms 20A and 20B contact each other have different sizes.

  In addition, the free end has a larger amplitude at the frequency of the vibration mode in which the vicinity of the outermost peripheral portion vibrates than the fixed end of the outermost peripheral portion of the diaphragm. Therefore, the sound pressure can be increased at some resonance frequencies with the free end.

  Also, when reproducing high-frequency sound and suppressing low-frequency sound, it is divided into two rather than having a single diaphragm, and the longest part of each diaphragm (X direction in the figure) By shortening the length and increasing the shape rigidity, the resonance frequency can be realized in a high frequency region (that is, the lowest resonance frequency is made higher than that of the single integrated diaphragm). Further, unnecessary low frequency sound reproduction can be suppressed.

  If the diaphragm is simply made smaller (ie, the longest part is shorter), the resonance frequency can be reduced, but the sound pressure is reduced because the area is smaller than that of the single diaphragm. Become. By dividing the diaphragm into two small parts, it is possible to prevent a decrease in sound pressure by keeping the resonance frequency high and keeping the total area equal to that of the single diaphragm.

  Further, in the above-described embodiment, even when the diaphragms 20A and 20B have the same characteristics, since a part of the diaphragm is a free end, the amplitude at the time of resonance is large and the entire circumference is fixed. In comparison, the sound pressure can be increased.

  In the above-described embodiment, the longest part of each diaphragm is smaller than the longest part of the diaphragm that is not divided, so that the lowest resonance frequency among the resonance frequencies is higher than that of the diaphragm that is not divided. . For this reason, sound quality adjustment when reproduction at a low frequency is unnecessary can be realized without maintaining the area equivalent to the diaphragm that is not divided and without reducing the sound pressure.

<2. Second Embodiment>
FIG. 3 is a diagram illustrating a configuration example of the speaker 110 according to the second embodiment. 3A is a top view of the speaker 110, and FIG. 3B is a cross-sectional view of the speaker 110 taken along line X1 in FIG. 3A. Since the speaker 110 has the same configuration as that of the speaker 100 of FIG.

  The damping material 40 is provided between the plurality of diaphragms 20A and 20B. The damping material 40 is in contact with each of the outer peripheral portions of the diaphragms 20A and 20B that are close to each other. As shown in FIG. 3, the damping material 40 has a substantially rectangular parallelepiped shape. The damping material 40 is provided outside the space formed by the frame 10 and the diaphragms 20A and 20B so as to close the gap G between the diaphragms 20A and 20B.

  As shown in FIG. 3A, the length of the damping material 40 in the longitudinal direction (Y-axis direction) is the same as the length of the free ends of the diaphragms 20A and 20B. Further, as shown in FIG. 3B, the damping material 40 is disposed so as to face the piezoelectric actuator 30 with the diaphragms 20A and 20B interposed therebetween. The damping material 40 converts the vibration at the free ends of the diaphragms 20A and 20B into, for example, heat energy and absorbs it.

  Here, the point which provides the damping material 40 in the outer peripheral part which is not in contact with the support wall 10B of diaphragm 20A, 20B is demonstrated. Since the fixed ends of the diaphragms 20A and 20B are in contact with the support wall 10B, they do not vibrate greatly. On the other hand, the free ends of the diaphragms 20A and 20B can vibrate freely when the damping material 40 is not provided. Therefore, depending on the frequency, the free ends of the diaphragms 20A and 20B may vibrate greatly, and an excessive peak may occur in the sound pressure frequency characteristics of the speaker 110.

  Therefore, in the speaker 110 according to the present embodiment, the damping material 40 is provided at the free ends of the diaphragms 20A and 20B, thereby appropriately suppressing the resonance generated at the free ends. Thereby, the excessive peak which generate | occur | produces in the sound pressure frequency characteristic of the speaker 110 can be suppressed, and deterioration of sound quality can be suppressed.

  Here, the case where the length of the damping material 40 in the longitudinal direction is the same as the length of the free ends of the diaphragms 20A and 20B has been described, but the present invention is not limited to this. It is only necessary to moderately suppress the resonance generated at the free ends of the vibration plates 20A and 20B by the vibration damping material 40, and even if the length in the longitudinal direction of the vibration damping material 40 is shorter than the length of the free ends of the vibration plates 20A and 20B. May be.

  Moreover, the shape of the damping material 40 is not limited to a rectangular parallelepiped shape, and may be any shape. Furthermore, there may be a plurality of vibration damping materials 40. For example, a plurality of damping materials 40 may be arranged along the gap G.

  Alternatively, the damping material 40 may include a first damping material that contacts the free end of the diaphragm 20A and a second damping material that contacts the free end of the diaphragm 20B. In this way, by providing the first and second damping materials in contact with the outer peripheries of the diaphragms 20A and 20B, respectively, for example, selecting the damping material according to the material of the diaphragms 20A and 20B and the resonance frequency, respectively. Can do.

<3. Third Embodiment>
FIG. 4 is a diagram illustrating a configuration example of the speaker 120 according to the third embodiment. 4A is a top view of the speaker 120, and FIG. 4B is a side view of the speaker 120. In addition, the same code | symbol is attached | subjected to the component same as the speaker 100 of FIG. 1, and description is abbreviate | omitted.

  As shown in FIG. 4, the speaker 120 includes a frame 11, a diaphragm 21, and a piezoelectric actuator 30.

  The diaphragm 21 is a plate-like member that vibrates according to the expansion and contraction of the piezoelectric actuator 30 and generates sound. The diaphragm 21 has a substantially rectangular vibration surface. The diaphragm 21 is made of a material such as a metal such as aluminum, iron or copper, a resin such as ABS resin, acrylic resin or polycarbonate, paper, or wood.

  The frame 11 has a substantially rectangular bottom surface 11A and a frame-shaped support wall 11B. The frame 11 is a box-shaped member having an open surface facing the bottom surface 11A. The support wall 11 </ b> B supports a part of the outer peripheral portion of the diaphragm 21. Specifically, the support wall 11B has a plurality of support members 11C and supports the diaphragm 21 via the plurality of support members 11C.

  The plurality of support members 11C are substantially rectangular parallelepiped members having the same thickness and a predetermined height as the support wall 11B. The plurality of support members 11C are integrally formed with the support wall 11B. Further, in the example of FIG. 4, the plurality of support members 11C are provided at substantially the center of each side of the support wall 11B.

  As shown in FIG. 4, in this embodiment, the support member 11 </ b> C of the support wall 11 </ b> B supports a part of the outer peripheral portion of the diaphragm 21. Thereby, the approximate center of each side of the outer peripheral portion of the diaphragm 21 is fixed by the plurality of support members 11C. Hereinafter, the outer peripheral portion of the diaphragm 21 supported by the support member 11 </ b> C is also referred to as a fixed end of the diaphragm 21. On the other hand, the corners of each side are not fixed by the plurality of support members 11C and vibrate freely. Hereinafter, a portion of the outer peripheral portion of the diaphragm 21 that is not in contact with the support member 11 </ b> C is also referred to as a free end of the diaphragm 21.

  Of the outer periphery of the diaphragm 21, the free end that is not in contact with the support member 11C is more likely to resonate than the fixed end that is in contact, and the types of resonance modes of the diaphragm 21 are increased. For this reason, the number of peak dips in the sound pressure frequency characteristic of the speaker 120 is reduced and flattened. In addition, in the outer peripheral portion of the moving plate 21, the free end that is not in contact with the support member 11 </ b> C has a larger amplitude during resonance of the diaphragm 21 than the fixed end that is in contact. For this reason, the sound pressure of the speaker 120 can be increased.

  As described above, the support member 11C of the support wall 11B supports a part of the outer peripheral portion of the diaphragm 21, whereby the sound pressure frequency characteristics of the speaker 120 can be flattened, and deterioration of sound quality can be suppressed. it can. Further, since the support member 11C of the support wall 11B supports a part of the outer peripheral portion of the diaphragm 21, the sound pressure can be increased at several resonance frequencies of the speaker 120.

  In general, a single piezoelectric element has a small amplitude. For this reason, a speaker using a piezoelectric element has a low sound pressure. As in this embodiment, the configuration including the free end has a larger amplitude than the fixed end, and can increase the sound pressure.

  Here, although the case where the number of the plurality of support members 11C is four has been described, the number of the plurality of support members 11C is not limited thereto. It is sufficient that the diaphragm 21 can be supported by the plurality of support members 11C, and the number may be more or less than four.

  Further, the arrangement of the plurality of support members 11C is not limited to the center of each side of the support wall 11B. For example, a plurality of support members 11C may be provided at the corners of each side of the support wall 11B. The corners of the diaphragm 21 are more likely to vibrate than the central part of each side. Therefore, by providing a plurality of support members 11C at the corners of each side of the support wall 11B, excessive resonance at the corners can be suppressed, and excessive peaks in the sound pressure frequency characteristics of the speaker 120 are suppressed. be able to. In addition, since the type of resonance frequency is different compared to the case where the support wall 11B is provided at the center of each side, the sound pressure frequency characteristics of the speaker 120 can be changed by changing the position where the support wall 11B is provided. The sound quality can be adjusted according to the performance required for the speaker 120.

  The shape of the plurality of support members 11C is not limited to a substantially rectangular parallelepiped shape. For example, when a plurality of support members 11C are provided at the corners of each side of the support wall 11B, the support members 11C may be L-shaped in accordance with the corners of the support wall 11B. Alternatively, the shape of the support member 11C may be, for example, a substantially trapezoidal shape in which the area in contact with the support wall 11B is larger than the area in contact with the diaphragm 21.

  As described above, the number, arrangement, or shape of the plurality of support members 11 </ b> C can be appropriately changed according to the sound pressure frequency characteristics of the speaker 120.

<3-1. Modification 1>
In addition, although FIG. 4 demonstrated the case where the number of the diaphragms 21 was one, the number of the diaphragms may be plural. FIG. 5 shows a speaker 130 having a plurality of diaphragms 20A and 20B. FIG. 5A is a top view of the speaker 130 according to the first modification, and FIG. 5B is a side view of the speaker 130.

  A speaker 130 illustrated in FIG. 5 includes diaphragms 20A and 20B, similarly to the speaker 100 illustrated in FIG. As described above, the plurality of diaphragms 20A and 20B may be supported by the plurality of support members 11C. Thereby, the number of free ends of the plurality of diaphragms 20A and 20B can be increased.

  The number, arrangement, or shape of the plurality of support members 11C can be changed as appropriate in accordance with the sound pressure frequency characteristics of the diaphragms 20A and 20B. By changing the number and arrangement of the plurality of support members 11C, for example, even if the diaphragms 20A and 20B are made of the same material, the resonance frequency can be varied.

  5 illustrates the case where the frame 10 of the speaker 100 illustrated in FIG. 1 is replaced with the frame 11 illustrated in FIG. 4, the present invention is not limited thereto. For example, the frame 10 of the speaker 110 shown in FIG. 3 may be replaced with the frame 11 shown in FIG. Or you may apply to each speaker of embodiment mentioned later.

<4. Fourth Embodiment>
FIG. 6 is a diagram illustrating a configuration example of the speaker 140 according to the fourth embodiment. 6A is a top view of the speaker 140, and FIG. 6B is a cross-sectional view of the speaker 140 taken along line X1 in FIG. 6A. In addition, the same code | symbol is attached | subjected to the component same as other embodiment, and description is abbreviate | omitted.

  As shown in FIG. 6, the speaker 140 includes a frame 10, a diaphragm 21, a piezoelectric actuator 30, and a support damping material 50.

  The support damping material 50 is a frame-shaped damping material having the same thickness and a predetermined height as the support wall 10B. The support damping material 50 is provided between the diaphragm 21 and the support wall 10B. The support damping material 50 supports the outer peripheral portion of the diaphragm 21. That is, the support wall 10 </ b> B supports the outer peripheral portion of the diaphragm 21 via the support damping material 50.

  The speaker 140 has a space formed by the frame 10, the support damping material 50 and the diaphragm 21. Moreover, the piezoelectric actuator 30 is arrange | positioned in this space.

  As described above, the support damping material 50 supports the outer peripheral portion of the diaphragm 21, so that unnecessary resonance of the outer peripheral portion of the diaphragm 21 can be suppressed. Thereby, an excessive peak on the sound pressure frequency characteristic of the speaker 140 can be suppressed, and the sound pressure frequency characteristic can be flattened. Therefore, deterioration of the sound quality of the speaker 140 can be suppressed.

  In addition, although the case where the number of the diaphragms 21 is one has been described here, the number of the diaphragms may be plural. For example, the support damping material 50 may be provided between the support wall 10B of the speakers 100 and 110 shown in FIGS. 1 and 3 and the plurality of diaphragms 20A and 20B. In this case, the support damping material 50 is disposed between the outermost peripheral portion of the region formed by the plurality of diaphragms and the support wall 10B.

<5. Fifth Embodiment>
FIG. 7 is a diagram illustrating a configuration example of the speaker 150 according to the fifth embodiment. FIG. 7A is a top view of the speaker 150, and FIG. 7B is a side view of the speaker 150. In addition, the same code | symbol is attached | subjected to the component same as other embodiment, and description is abbreviate | omitted.

  As shown in FIG. 7, the speaker 150 includes a frame 10, a diaphragm 21, a piezoelectric actuator 30, and a plurality of support vibration damping materials 51 </ b> A to 51 </ b> D (hereinafter also referred to as support vibration damping materials 51).

  The plurality of support vibration damping materials 51 are substantially rectangular parallelepiped vibration damping materials having the same thickness and a predetermined height as the support wall 10 </ b> B of the frame 10. The support damping material 51 is provided between the diaphragm 21 and the support wall 10B. In the present embodiment, as shown in FIG. 7, the plurality of support damping materials 51 are arranged at substantially the center of each side of the support wall 10B. The support wall 10 </ b> B supports the outer peripheral portion of the diaphragm 21 via a plurality of support damping materials 51.

  Thereby, the approximate center of each side of the outer peripheral portion of the diaphragm 21 is supported by the support wall 10 </ b> B via the plurality of support damping materials 51. On the other hand, the corners of each side vibrate freely without being supported via the plurality of support damping materials 51.

  A portion of the outer peripheral portion of the diaphragm 21 that is not supported by the support wall 10B is likely to resonate, and the types of resonance modes of the diaphragm 21 increase. Moreover, since the part supported by the support wall 10B among the outer peripheral parts of the diaphragm 21 is supported via the support damping material 51, unnecessary resonance of the outer peripheral part is suppressed, and the sound pressure frequency of the diaphragm 21 is reduced. An excessive peak in characteristics can be suppressed. Thereby, the sound pressure frequency characteristic of the speaker 150 can be flattened, and deterioration of the sound quality of the speaker 150 can be suppressed. Further, the amplitude of the unsupported portion of the outer peripheral portion of the diaphragm 21 is increased, and the sound pressure of the speaker 150 can be increased. When the amplitude becomes excessively large, the sound pressure frequency characteristic has a peak. However, the excessive vibration can be suppressed by the vibration damping action of the support damping material 51 that receives the reaction of the resonance at the time of excessive amplitude, and the speaker 150. The sound pressure can be increased while maintaining the flatness of the sound pressure frequency characteristic.

  In addition, although the case where the number of the diaphragms 21 is one has been described here, the number of the diaphragms may be plural. For example, a plurality of support damping materials 51 may be provided between the support walls 10B of the speakers 100 and 110 shown in FIGS. 1 and 3 and the plurality of diaphragms 20A and 20B. In this case, the support damping material 51 is disposed between the outermost peripheral portion of the region formed by the plurality of diaphragms and the support wall 10B.

<6. Sixth Embodiment>
FIG. 8 is a diagram illustrating a configuration example of the speaker 160 according to the sixth embodiment. 8A is a top view of the speaker 160, and FIG. 8B is a side view of the speaker 160. In addition, the same code | symbol is attached | subjected to the component same as other embodiment, and description is abbreviate | omitted.

  A speaker 160 shown in FIG. 8 includes a frame 12, a diaphragm 21, a piezoelectric actuator 30, and a plurality of support vibration damping materials 52A and 52B (hereinafter also referred to as support vibration damping materials 52).

  The frame 12 has a substantially rectangular bottom surface 12A and a frame-shaped support wall 12B. The frame 12 is a box-shaped member having an open surface facing the bottom surface 12A. The support wall 12B has a plurality of support members 12C.

  The plurality of support members 12C are substantially rectangular parallelepiped members having the same thickness and a predetermined height as the support wall 12B. The length of the support member 12C in the longitudinal direction (X-axis direction in FIG. 8A) is substantially the same as the length of the vibration plate 21 in the longitudinal direction (X-axis direction in FIG. 8A) excluding the thickness of the support damping material 52. The same.

  The plurality of support members 12C are provided between the outer peripheral portion in the longitudinal direction of the diaphragm 21 and the support wall 12B. In the example shown in FIG. 8A, two support members 12C are provided substantially in parallel. The support wall 12B supports the outer peripheral portion in the longitudinal direction of the diaphragm 21 through the plurality of support members 12C. The support member 12C may be integrally formed with the support wall 12B.

  The plurality of support vibration damping materials 52 are substantially rectangular parallelepiped vibration damping materials having the same thickness as the support wall 12B and the same height as the support member 12C. The length of the support damping material 52 in the longitudinal direction (Y-axis direction in FIG. 8A) is substantially the same as the length of the diaphragm 21 in the short direction (Y-axis direction in FIG. 8A).

  The plurality of support damping materials 52 are provided between the outer peripheral portion of the diaphragm 21 in the short direction and the support wall 12B. The support wall 12 </ b> B supports the outer peripheral portion of the diaphragm 21 in the short direction through the plurality of support damping materials 52.

  The speaker 160 has a space formed by the frame 12, the support damping material 52 and the diaphragm 21. Moreover, the piezoelectric actuator 30 is arrange | positioned in this space.

  As described above, the outer periphery of the diaphragm 21 is in contact with both the support damping material 52 and the support wall 12B, so that excessive resonance of the outer periphery is suppressed, and an excessive peak on the sound pressure frequency characteristic of the diaphragm 21 is suppressed. Can be suppressed. Thereby, the sound pressure frequency characteristic of the speaker 160 can be flattened, and deterioration of the sound quality of the speaker 160 can be suppressed.

  In addition, although the case where the number of the diaphragms 21 is one has been described here, the number of the diaphragms may be plural. For example, the support member 12C and the support damping material 52 may be provided between the support wall 10B of the speakers 100 and 110 shown in FIGS. 1 and 3 and the plurality of diaphragms 20A and 20B. In this case, the support member 12C and the support damping material 52 are disposed between the outermost peripheral portion of the region formed by the plurality of diaphragms 20A and 20B and the support wall 12B.

  Further, the number, arrangement, or shape of the plurality of support members 12 </ b> C and the plurality of support damping materials 52 can be appropriately changed according to the sound pressure frequency characteristics of the diaphragm 21. Further, as shown in FIGS. 5 and 7, a part of the outer peripheral portion of the diaphragm 21 may not be in contact with the plurality of support members 12 </ b> C and the plurality of support vibration damping materials 52. Thus, a part of the outer peripheral part of the diaphragm 21 may be made to easily resonate by providing a gap between a part of the outer peripheral part of the diaphragm 21 and the support wall 12B.

<7. Seventh Embodiment>
FIG. 9 is a diagram illustrating a configuration example of the speaker 170 according to the seventh embodiment. 9A is a top view of the speaker 170, and FIG. 9B is a cross-sectional view of the speaker 170 taken along line X1 in FIG. 9A.

  A speaker 170 shown in FIG. 9 includes a frame 13, diaphragms 22A and 22B, and piezoelectric actuators 30A and 30B.

  The diaphragm 22A is a plate-like member that vibrates according to the expansion and contraction of the piezoelectric actuator 30A and generates sound. The diaphragm 22B is a plate-like member that vibrates according to the expansion and contraction of the piezoelectric actuator 30B and generates sound. The diaphragms 22A and 22B have a substantially rectangular vibration surface. The diaphragms 22A and 22B are arranged so that the vibration surfaces are substantially on the same plane (the XY plane in FIG. 1).

  The diaphragms 22A and 22B shown in FIG. 9 have different sizes. The diaphragms 22A and 22B have different resonance frequencies. The materials of the diaphragms 22A and 22B are the same as those of the diaphragms 20A and 20B shown in FIG.

  The frame 13 includes a substantially rectangular bottom surface 13A, a frame-shaped support wall 13B, and a partition wall 13C. The frame 13 is a box-shaped member having an open surface facing the bottom surface 13A. The support wall 13B supports the outermost peripheral portion of the region formed by the diaphragms 22A and 22B. The support wall 13B is in contact with the outer peripheral portion of the diaphragms 22A and 22B excluding the adjacent sides.

  The partition wall 13C supports the outer peripheral portion of at least one diaphragm among the plurality of diaphragms 22A and 22B. In the example of FIG. 9, the partition wall 13C supports the outer peripheral portions of the diaphragms 22A and 22B that are close to each other.

  The partition wall 13C divides the space formed by the frame 13 and the diaphragms 22A and 22B into a first space including the piezoelectric actuator 30A and a second space including the piezoelectric actuator 30B. As a result, the speaker 170 has a first space and a second space.

  The partition wall 13C has a recess 60 that allows the first space and the second space to communicate with each other. Moreover, the recessed part 60 is a shape which the outer peripheral part of each of several diaphragm 22A, 22B touches the partition wall 13C over the direction (Y-axis direction of FIG. 9) along the partition wall 13C. This point will be described in detail with reference to FIG.

  FIG. 10 is a diagram for explaining the details of the recess 60. FIG. 10A is an enlarged view of the region R1 in FIG. 9A, and FIG. 10B is a view of the region R1 as viewed from the X-axis direction.

  The recess 60 is provided at the end of the partition wall 13C on the plurality of diaphragms 22A, 22B side (Z-axis positive direction). That is, the recess 60 has a plurality of diaphragms 22A and 22B side (Z-axis positive direction) opened, and the diaphragms 22A and 22B are arranged on the partition wall 13C, thereby including the piezoelectric actuator 30A. The through hole communicates with a space including the piezoelectric actuator 30B.

  As illustrated in FIG. 10A, the partition wall 13C includes convex portions 13D to 13F. The convex portion 13D is a wall that is located approximately at the center in the thickness direction (X-axis direction) of the partition wall 13C and extends from the positive direction of the Y-axis of the concave portion 60 to the negative direction. Further, the convex portions 13E and 13F are walls respectively positioned at both ends in the thickness direction of the partition wall 13C and extending from the negative direction of the concave portion 60 in the positive direction. Due to the convex portions 13D to 13F, the concave portion 60 has a bent path.

  Further, the length L1 of the convex portion 13D in the Y-axis direction is equal to or larger than the width L2 of the concave portion 60 in the direction along the partition wall 13C (Y-axis direction) (L1 ≧ L2). FIG. 10A shows a case where L1 = L2. Accordingly, the outer peripheral portions of the diaphragms 22A and 22B are in contact with the partition wall 13C at any position in the short direction of the partition wall 13C in the longitudinal direction of the partition wall 13C. Therefore, as shown in FIG. 10B, when the partition wall 13C is viewed from the X-axis direction, the space connected through the concave portion 60 is not visible, and the concave portion 60 appears to be blocked by the convex portion 13D.

  As described above, in this embodiment, the outer peripheral portion of the diaphragms 22A and 22B is provided by providing the convex portion 13D that blocks the opening between the opening on the first space side and the opening on the second space side of the recess 60. However, the partition wall 13C and the support wall 13B are in contact with each other at any position. That is, the outer peripheral portions of the diaphragms 22A and 22B are both fixed ends.

  The speaker 170 according to the present embodiment vibrates the two diaphragms 22A and 22B with the piezoelectric actuators 30A and 30B, respectively, so that the sound pressure frequency characteristics of the two diaphragms 22A and 22B are obtained as the sound pressure frequency characteristics of the speaker 170. Overlapping characteristics can be obtained. Therefore, the sound pressure frequency characteristic of the speaker 170 can be flattened, and the speaker 170 can suppress deterioration in sound quality.

  Further, if the speaker 170 is simply divided into the first space and the second space by the partition wall 13C, when the speaker 170 is operated, a force is generated in the positive direction of the Z axis in FIG. 9, and the diaphragms 22A and 22B are peeled off. There is a possibility. Therefore, in this embodiment, the recess 60 is provided in the partition wall 13C. Thereby, the force generated in the Z-axis direction can be suppressed, and peeling of the diaphragms 22A and 22B can be suppressed.

  In the case of providing the recess 60, as described above, the outer peripheral portions of the diaphragms 22A and 22B are in contact with any one of the partition walls 13C in the longitudinal direction of the partition wall 13C. Thereby, the outer peripheral part of diaphragm 22A, 22B will be in contact with either the partition wall 13C or the support wall 13B, and the unnecessary resonance which generate | occur | produces in the outer peripheral part of diaphragm 22A, 22B can be suppressed. Thereby, the sound pressure frequency characteristic of the speaker 170 can be flattened, and the speaker 170 can suppress deterioration of sound quality.

  Next, the connection hole will be described. The air on the back of the diaphragm acts as an air spring that supports the diaphragm. For this reason, the elastic modulus of the air spring changes (that is, the resonance point changes) depending on the volume of the space surrounded by the side and bottom surfaces of the frame, and the sound pressure frequency characteristic changes. In order to obtain a good sound pressure frequency characteristic, it is necessary to appropriately set the volume of the space surrounded by the side surface and the bottom surface of the frame.

  However, if the size of the outermost speaker shape is determined due to the limitation of the installation space, there is a possibility that only a volume smaller than the required volume can be obtained.

  Therefore, as shown in FIGS. 9 to 12, in the case of a frame structure in which each of the two diaphragms is attached in front of separate air chambers and both are integrated, holes are formed in the partitions of both air chambers. If it opens and connects, each diaphragm can also use the next air chamber as a volume. For this reason, the volume can be increased without increasing the external dimension of the speaker, and good sound pressure frequency characteristics can be obtained. The method of connecting the air chambers is to make a hole in the vicinity of the center of the partition wall as shown in FIG. 12 because it is necessary to secure the attachment surface of the diaphragm of the frame.

  However, if a hole is made near the center of the partition wall, when the frame is manufactured by resin molding, the hole is perpendicular to the direction in which the mold is formed (the direction in which the mold is pulled out, the Z direction). Cannot be formed with a mold (cannot be removed from the mold). Moreover, if it can form with a metal mold | die at the time of resin molding (when a metal mold | die comes off), the shape of a hole will become a simple notch-shaped hole (recessed part), and the diaphragm sticking surface will be interrupted. In the case of a so-called slide mold structure, the mold structure becomes complicated and the cost further increases.

  Therefore, by adopting the configuration shown in FIGS. 9 to 11, the frame can be formed by a mold (disengaged from the mold), and the vibration pasting surface cannot be interrupted.

<7-1. Modification 2>
Note that the shape of the recess 60 is not limited to the example shown in FIG. For example, as shown in FIG. 11, the recess 61 may be provided obliquely in the longitudinal direction of the partition wall 13C (Y-axis direction in FIG. 11).

  A partition wall 13C shown in FIG. 11 has tapered portions 13G and 13H. The concave portions 61 are provided so that the top portions of the tapered portions 13G and 13H overlap each other by a distance L3 (L3 ≧ 0) in the Y-axis direction. Thus, when the partition wall 13C is viewed from the X-axis direction, the space connected through the recess 61 is not visible, and the recess 61 appears to be blocked by the tapered portions 13G and 13H.

  In this way, by preventing the opening on the first space side and the opening on the second space side of the recess 61 from overlapping with each other when viewed from the X-axis direction, the outer peripheral portions of the diaphragms 22A and 22B can be positioned at any position. You may make it contact | connect the partition wall 13C and the support wall 13B.

  In addition, the shape of the recessed parts 60 and 61 mentioned above is not restricted to the example mentioned above. The outer peripheral part of diaphragm 22A, 22B should just become a fixed end, and the recessed parts 60 and 61 may be bent several times, for example, may be a curve.

<7-2. Modification 3>
FIG. 12 is a cross-sectional view of the speaker 180 according to the third modification. Since the speaker 180 has the same configuration as that of the speaker 170 of FIG. 10 except for the through-hole 62, the same components are denoted by the same reference numerals and description thereof is omitted.

  The through hole 62 is provided at the approximate center in the Z-axis direction of the partition wall 13C. The through hole 62 may have a bent path or an oblique path in plan view as shown in FIGS. 10 and 11, or may be a straight path parallel to the X axis.

  By providing the through hole 62 substantially at the center in the height direction (Z-axis direction) of the partition wall 13C, the shape of the through hole 62 can be appropriately changed.

  As described above, the outer peripheral portions of the diaphragms 22A and 22B may be in contact with the partition wall 13C in the longitudinal direction of the partition wall 13C, and the shapes and positions of the recesses 60 and 61 and the through holes 62 are limited to the above-described examples. I can't.

  In the seventh embodiment, the speaker 170 is divided into two spaces by the partition wall 13C. However, the present invention is not limited to this. For example, two speakers may be connected to form one speaker. In this case, a recess may be provided in each of the supporting walls to be connected.

  In the seventh embodiment, the diaphragms 22A and 22B are arranged so that the short sides of the diaphragms 22A and 22B are in contact with each other, but the present invention is not limited to this. The diaphragms 22A and 22B may be arranged so that the longitudinal directions of the diaphragms 22A and 22B are in contact with each other.

  Further, for example, as shown in FIGS. 1 and 3, the diaphragms 22 </ b> A and 22 </ b> B may be configured by a plurality of diaphragms. Alternatively, as illustrated in FIGS. 4 to 8, the support wall 13 </ b> B and the partition wall 13 </ b> C of the frame 13 may support a part of the outer peripheral portion of the diaphragms 22 </ b> A and 22 </ b> B. Support vibration damping materials 51 and 52 may be provided between 13C and 13C.

<8. Eighth Embodiment>
FIG. 13 is a diagram illustrating a configuration example of the speaker 190 according to the eighth embodiment. FIG. 13A is a top view of the speaker 190, and FIG. 13B is a side view of the speaker 190.

  The speaker 190 is formed by stacking two diaphragms having different resonance modes (different resonance frequencies), and is emitted from the diaphragm 23A and emitted from the diaphragm 23B through the diaphragm 23A. The object is to flatten the sound pressure frequency characteristic by the interference with sound and the principle shown in FIGS. 2A and 2B. In other words, in the configuration example of FIG. 1A to FIG. 1C described above, a plurality of diaphragms are arranged side by side to exert the flattening effect shown in FIG. 2A and FIG. 2B, but the configuration example shown in FIG. Is intended to exhibit the flattening effect shown in FIGS. 2A and 2B by arranging a plurality of diaphragms vertically stacked. It is not shown that one diaphragm is advantageous for low frequency reproduction, and the other diaphragm is advantageous for high frequency reproduction.

  Further, as shown in FIG. 2A, when the plurality of diaphragms 23A and 23B are individually vibrated, the peak dip of the sound pressure frequency characteristic is increased, and the sound quality is deteriorated. In view of this, the speaker 190 according to the present embodiment has a plurality of diaphragms 23 </ b> A and 23 </ b> B arranged in the Z direction and vibrated by the piezoelectric actuator 31. As a result, the peak dips of the sound pressure frequency characteristics of the diaphragms 23A and 23B cancel each other, and the sound pressure frequency characteristics of the speaker 190 become flat as shown in FIG. 2B.

  That is, the speaker 190 according to the present embodiment flattens the sound pressure frequency characteristics of the speaker 190 by vibrating the diaphragms 23A and 23B arranged in a direction perpendicular to the plane of the diaphragm with the piezoelectric actuator 31. it can. Thereby, the speaker 190 can suppress deterioration of sound quality.

  A speaker 190 shown in FIG. 13 includes a frame 15, diaphragms 23A and 23B, a piezoelectric actuator 31, and a plurality of support members 70A to 70D (hereinafter also referred to as support members 70). The frame 15, the diaphragms 23A and 23B, and the piezoelectric actuator 31 are the same as the diaphragms 20A and 20B shown in FIG.

  The diaphragms 23A and 23B according to the present embodiment are arranged so that the vibration surfaces are substantially parallel. Specifically, the piezoelectric actuators 31 are arranged apart from each other in the Z-axis direction in FIG. 13A by the same thickness.

  The piezoelectric actuator 31 is provided between the diaphragms 23A and 23B. The piezoelectric actuator 31 is provided in contact with each of the adjacent diaphragms 23A and 23B. Specifically, the piezoelectric actuator 31 is disposed such that one surface is in contact with the vibration surface of the vibration plate 23A, and the opposite surface facing the one surface is in contact with the vibration surface of the vibration plate 23B. Thereby, the piezoelectric actuator 31 vibrates both the diaphragms 23A and 23B.

  The support member 70 is provided between the diaphragms 23A and 23B. The support member 70 is provided in contact with the outer peripheral portions of the adjacent diaphragms 23A and 23B. Thereby, the support member 70 supports the diaphragm 23A. The thickness of the support member 70 (length in the Z-axis direction) is substantially the same as the thickness of the piezoelectric actuator 31 (length in the Z-axis direction).

  The support member 70 is made of a material such as a metal such as aluminum, a resin, and wood. The support member 70 may be made of the same material as that of the frame 15, for example. Or you may comprise the supporting member 70 with a damping material.

  The frame 15 supports the outer periphery of the diaphragm 23B. In the example shown in FIG. 13B, the case where the frame 15 supports the entire outer peripheral portion of the diaphragm 23B is shown, but the present invention is not limited to this. For example, as shown in FIGS. 4 to 8, the frame 15 may support a part of the outer peripheral portion of the diaphragm 23 </ b> B, and a support damping material between the frame 15 and the outer peripheral portion of the diaphragm 23 </ b> B. 51 and 52 may be provided.

  The speaker 190 according to the present embodiment can flatten the sound pressure frequency characteristics of the speaker 190 by vibrating the diaphragms 23A and 23B arranged substantially in parallel with the piezoelectric actuator 31. Thereby, the speaker 190 can suppress deterioration of sound quality.

  Specifically, a relatively good sound pressure can be obtained in a low frequency region by the vibration of the diaphragm 23B having an outer peripheral portion fixed by the frame 15 according to the expansion and contraction of the piezoelectric actuator 31. In addition, the diaphragm 23A having a part of the outer periphery fixed by the support member 70 vibrates in accordance with the expansion and contraction of the piezoelectric actuator 31, whereby a relatively good sound pressure can be obtained in a high frequency region.

  Therefore, when the diaphragms 23A and 23B vibrate according to the expansion and contraction of the piezoelectric actuator 31, a good sound pressure can be obtained in a wide frequency range, and deterioration of the sound quality of the speaker 190 can be suppressed.

  Moreover, since the diaphragms 23A and 23B are arranged substantially in parallel, the speaker 190 can be reduced in size. Furthermore, by making the thickness of the support member 70 and the thickness of the piezoelectric actuator 31 substantially the same, it is possible to suppress an increase in the thickness of the speaker 190 (the length in the Z-axis direction in FIG. 13). That is, it is possible to suppress deterioration of sound quality while realizing a reduction in size and thickness of the speaker 190.

  Note that the number, arrangement, or shape of the support members 70 can be changed as appropriate in accordance with the sound pressure frequency characteristics of the speaker 190. Further, the sizes of the diaphragms 23A and 23B can be appropriately changed according to the sound pressure frequency characteristics of the speaker 190. At this time, the size of the diaphragms 23A and 23B is not necessarily the same. Further, the number of diaphragms 23A and 23B is not limited to two and may be two or more.

<8-1. Modification 4>
FIG. 14 is a top view illustrating a configuration example of the speaker 200 according to the fourth modification. Since the speaker 200 has the same configuration as the speaker 190 of FIG. 13 except for the diaphragm 24A, the same components are denoted by the same reference numerals and description thereof is omitted.

  The diaphragm 24 </ b> A has at least one hole 80. The hole 80 is a sound emission hole for emitting sound emitted from one diaphragm 23 </ b> B whose outer peripheral portion is supported by the support wall of the frame 15 from the other diaphragm 24 </ b> A to the outside of the speaker 200.

  Thus, by providing the hole 80 in the diaphragm 24A provided outside the speaker 200, the radiation efficiency of sound generated from the diaphragm 23B provided inside the speaker 200 can be improved.

  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.

10-13, 15 Frame 20-24 Diaphragm 30, 31 Piezoelectric actuator 40 Damping material 50-52 Support damping material 60, 61 Recess 62 Through hole 70 Support member

Claims (10)

A piezoelectric actuator that expands and contracts according to a given voltage;
A plurality of diaphragms that generate sound by vibrating at different resonance frequencies according to the expansion and contraction of the piezoelectric actuator,
A speaker comprising: The plurality of diaphragms are arranged such that vibration surfaces are substantially coplanar,
The speaker according to claim 1, wherein the piezoelectric actuator is provided so as to be in contact with the vibration surfaces of the plurality of diaphragms. Among the plurality of diaphragms, further comprising a damping material provided between adjacent diaphragms,
The speaker according to claim 1, wherein the damping material is in contact with each of the adjacent outer peripheral portions of the adjacent diaphragms. The speaker according to claim 1, further comprising a frame having a support wall that supports at least a part of an outermost peripheral portion of an area formed by the plurality of diaphragms. The speaker according to claim 4, further comprising a support damping material that is provided between the support wall and the outermost peripheral portion and supports the outermost peripheral portion. The speaker according to claim 5, wherein the outermost peripheral portion is in contact with each of the support damping material and the support wall. A second piezoelectric actuator arranged to be in contact with a diaphragm different from the diaphragm in contact with the piezoelectric actuator among the plurality of diaphragms;
The frame is
A partition wall that divides a space formed by the frame and the plurality of diaphragms into a first space including the piezoelectric actuator and a second space including the second piezoelectric actuator;
The partition wall is
A concave portion for communicating the first space and the second space on the plurality of diaphragm sides;
The recess is
The speaker according to any one of claims 4 to 6, wherein each of the plurality of diaphragms has a shape in contact with the partition wall in a direction along the partition wall. The plurality of diaphragms are provided such that vibration surfaces are substantially parallel,
The speaker according to claim 1, wherein the piezoelectric actuator is provided between the plurality of diaphragms. A support member provided between adjacent diaphragms of the plurality of diaphragms and in contact with each outer peripheral portion of the adjacent diaphragm;
The speaker according to claim 8, wherein the piezoelectric actuator is provided between the adjacent diaphragms and in contact with each of the adjacent diaphragms. A support wall that supports an outer peripheral portion of one of the adjacent diaphragms;
The speaker according to claim 9, wherein the other of the adjacent diaphragms has at least one hole.

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