WO2008143463A2

WO2008143463A2 - A sound converting apparatus

Info

Publication number: WO2008143463A2
Application number: PCT/KR2008/002839
Authority: WO
Inventors: Kwan-Ho Ko; Seung-Kiu Jeong; Sang-Moon Hwang
Original assignee: Em-Tech. Co., Ltd.
Priority date: 2007-05-21
Filing date: 2008-05-21
Publication date: 2008-11-27
Also published as: WO2008143463A3; KR20080102656A

Abstract

A sound converting apparatus vibrates a diaphragm (30) through the volume variations of a piezoelectric element (40). The sound converting apparatus includes: a piezoelectric element (40); a diaphragm (30) having an inner attachment portion (31 ) to be attached to the piezoelectric element (40), and a vibrating portion (32) being stretched or folded according to the transformation of the piezoelectric element; and a frame (20) having a recess (22) and a diaphragm seat positioned near the recess (22), to which an outer attachment portion (32a) of the diaphragm is attached.

Description

A SOUND CONVERTING APPARATUS

Technical Field

[1] The present invention relates to a sound converting apparatus, and more particularly, to a sound converting apparatus for vibrating a diaphragm through the transformation of a piezoelectric element. Background Art

[2] Among other sound converting apparatuses, the speaker changes electric energy to mechanical energy using a voice coil existing in an air gap according to the Fleming's left hand rule, "A current carrying conductor receives a force in a magnetic field." That is, when a current signal having various frequencies is applied to a voice coil, the voice coil generates mechanical energy corresponding to the intensity of current and the magnitude of frequency and makes a diaphragm attached to the voice coil vibrate, consequently producing a sound pressure of a certain level which can be perceived by the human ear.

[3] A magnetic circuit of such a speaker is designed in a manner that a magnetic flux can be linked to the voice coil in the air gap at right angles using a magnet (permanent magnet) and a top plate (or an upper plate) in a yoke made of a ferrous metal. The voice coil is adhered to the diaphragm and generates an exciting force in a vertical direction in response to an input signal, so that the diaphragm attached and bound to a frame vibrates and a sound pressure is generated. The diaphragm has waves of various shapes to obtain dynamic response but remove buckling behaviors during the vertical vibration. In fact, shape of the diaphragm acts as the most dominant design factor affecting the frequency characteristics.

[4] Fig. 1 is a cross-sectional view of a sound converting apparatus in the related art.

[5] Referring to Fig. 1, a conventional sound converting apparatus includes a frame 1, a yoke 2 inserted and mounted inside the frame 1, an inner ring magnet 3 and an outer ring magnet 4 for transferring a magnetic force to the joke 2 or receiving the magnetic force from the yoke 2, an inner ring top plate 5 and an outer ring top plate 6 for receiving the magnetic force from the inner ring magnet 3 or the outer ring magnet 4 to transfer the magnetic force to a voice coil 7 at right angles, the voice coil 7 partially inserted into an air gap between the inner ring magnet 3 and the inner ring top plate 5 and an air gap between the outer ring magnet 4 and the outer ring top plate 6, a diaphragm 8 with the voice coil 7 attached inside, for generating vibration by the vertical movement of the voice coil 7, and a protector 10 having a sound emission hole

11 and protecting the diaphragm 8. [6] As the conventional sound converting apparatus has a complicated structure including a frame, yoke, magnet, top plate, voice coil, diaphragm, and so on, it is not easy to manufacture and the apparatus could not be made thinner at a certain point. [7] Moreover, the magnetic flux is reduced when the joke, magnet, and top plate of smaller thickness are used. Further, when a vibration space for the diaphragm was reduced, the diaphragm comes in contact with the top plate or the protector and a sound from the touch is produced, only distorting the sound. Because of these, it is also difficult to make a small-size device (e.g., a portable terminal) incorporating the sound converting apparatus. [8] Also, a clipping phenomenon is observed in the conventional sound converting apparatus as the voice coil leaves the magnetic field at a high output, causing sound distortion.

Disclosure of Invention

Technical Problem [9] The present invention is conceived to solve the aforementioned problems in the prior art. An object of the present invention is to provide a sound converting apparatus for producing sound through a simple configuration. [10] Another object of the present invention is to provide a sound converting apparatus that features a minimal size and thickness to achieve miniaturization of the apparatus. [11] Still another object of the present invention is to provide a sound converting apparatus free of sound distortion and a clipping phenomenon. [12] Yet another object of the present invention is to provide a sound converting apparatus capable of producing sound at low power.

Technical Solution [13] According to an aspect of the present invention, there is provided a sound converting apparatus, including: a piezoelectric element; a diaphragm having an inner attachment portion to be attached to the piezoelectric element, and a vibrating portion being stretched or folded according to the transformation of the piezoelectric element; and a frame having a recess and a diaphragm seat positioned near the recess, to which an outer attachment portion of the diaphragm is attached. [14] In an exemplary embodiment of the invention, the inner attachment portion is adhered to an upper or lateral face of the piezoelectric element. [15] In an exemplary embodiment of the invention, the inner attachment portion is adhered circumferentially surrounding the upper or lateral face of the piezoelectric element.

[16] In an exemplary embodiment of the invention, the piezoelectric element includes at least a first and a second piezoelectric element layer, having the same polarization direction for each, or opposite polarization directions.

[17] In an exemplary embodiment of the invention, the frame has a support inside the recess, for supporting the piezoelectric element.

[18] In an exemplary embodiment of the invention, the support is connected to the center of the piezoelectric element.

[19] In an exemplary embodiment of the invention, the sound converting apparatus fiirther includes: a second piezoelectric element underneath the piezoelectric element, a connecting portion for connecting the piezoelectric element with the second piezoelectric element, and a second support for supporting the second piezoelectric element inside the recess.

[20] In an exemplary embodiment of the invention, the recess includes a second recess underneath the second piezoelectric element.

[21] In an exemplary embodiment of the invention, the vibrating portion is formed into a dome shape between the inner attachment portion and the outer attachment portion.

[22] In an exemplary embodiment of the invention, an apex of the dome portion is relatively thinner than the periphery of the dome portion.

[23] Another aspect of the present invention provides a sound converting apparatus, including: a piezoelectric element; a diaphragm having a piezoelectric attachment portion to be attached to one end of the piezoelectric element, and a vibrating portion being stretched or folded according to the transformation of the piezoelectric element; and a frame having a recess for housing the piezoelectric element and the diaphragm therein, a diaphragm seat attached by a frame attachment portion of the diaphragm on the periphery of the recess, and a support attached by the other end of the piezoelectric element.

[24] Still another aspect of the present invention provides a sound converting apparatus, including: a piezoelectric element having a first piezoelectric element layer and a second piezoelectric element layer, having the same polarization direction for each; a diaphragm having a connecting portion to be connected to one side of the piezoelectric element, and a vibrating portion surrounding the piezoelectric element connecting portion and being stretched or folded according to the transformation of the piezoelectric element; and a frame having a recess for housing the piezoelectric element and the diaphragm therein, a diaphragm seat attached by a frame attachment portion of the diaphragm on the periphery of the recess, and a support for supporting the piezoelectric element inside the recess.

Advantageous Effects [25] The sound converting apparatus of the present invention can produce sound through a markedly simplified structure as compared to that of the related art. [26] In addition, miniaturization of the sound converting apparatus is achieved by keeping the size and thickness of apparatus to a minimum. [27] Wth the direct transfer of the piezoelectric element transformation to the diaphragm, the sound converting apparatus of the present invention is now free of the problems of sound distortion and clipping phenomenon. [28] The sound converting apparatus of the present invention can produce a high sound pressure with the help of the piezoelectric element operating even at low power, and through the adjustment of thickness of the dome portion.

Brief Description of the Drawings

[29] Fig. 1 is a cross-sectional view of a conventional sound converting apparatus;

[30] Fig. 2 through Fig. 4 are cross-sectional views of a sound converting apparatus, in accordance with a first embodiment of the present invention;

[31] Fig. 5 is a perspective view of the sound converting apparatus shown in Fig. 2;

[32] Fig. 6 through Fig. 9 are cross-sectional views of a sound converting apparatus, in accordance with a second embodiment of the present invention; [33] Fig. 10 is a cross-sectional view of a sound converting apparatus, in accordance with a third embodiment of the present invention; [34] Fig. 11 is a cross-sectional view of a sound converting apparatus, in accordance with a fourth embodiment of the present invention; [35] Fig. 12 is a cross-sectional view of a sound converting apparatus, in accordance with a fifth embodiment of the present invention; [36] Fig. 13 is a cross-sectional view of a sound converting apparatus, in accordance with a sixth embodiment of the present invention;

[37] Fig. 14 is a perspective view of the sound converting apparatus of Fig. 13; and

[38] Fig. 15 is a cross-sectional view of a sound converting apparatus, in accordance with a seventh embodiment of the present invention. [39] Mode for the Invention

[40] Hereinafter, preferred embodiments of a sound converting apparatus will be described in detail with reference to the accompanying drawings.

[41] Fig. 2 through Fig. 4 are cross-sectional views of a sound converting apparatus, in accordance with a first embodiment of the present invention, and Fig. 5 is a perspective view of the sound converting apparatus shown in Fig. 2. Figs. 2 thrαgh 4 are cross-sectional views taken along line A-A' of Fig. 5.

[42] Referring to Fig. 2, a sound converting apparatus according to the present invention includes a frame 20 having a recess 22 formed inside, a diaphragm 30 seated on a diaphragm seat 24 provided to the frame 20, and a piezoelectric element 40 attached to the diaphragm 30.

[43] For the frame 20, the diaphragm seat 24 attached by the diaphragm 30 is positioned near the recess 22 and the inner space of the recess 22 serves as a resonance space. A protector (not shown) can be seated on the diaphragm seat 24 from the top of the diaphragm 30. A thrαigh hole (not shown) as an air inlet is formed in the bottom of the frame 20 to communicate the inner space of the recess 22 with outside.

[44] The diaphragm 30 includes an attachment portion (or inner attachment portion) to which the piezoelectric element 40 is bonded, and dome portions 32 extended from the attachment portion 31 in a dome shape, expanding or contracting according to volume variations of the piezoelectric element 40. The attachment portion 31, being bonded to the piezoelectric element 40, expands or contracts at the same time as the volume variations of the piezoelectric element 40, so that the dome portions 32 on both sides of the attachment portion 31 may expand or contract as well. The dome portions 32 are connected to the attachment portion 31, and each has an outer attachment portion 32a placed at the diaphragm seat 24. The thickness dl at the apex of the dorm portion 32 is relatively thinner than the thickness d2 of the periphery portion. Considering that the apex of the dorm portion 32 is the major area where expansion or contraction depending on the volume variations of the piezoelectric element 40 takes place, its relatively thin thickness facilitates the expansion or contraction of the dorm portion 32. To facilitate the expansion or contraction of the dorm portion 32 farther, the dorm portion 32 is preferably made of a flexible material.

[45] The piezoelectric element 40 has a specific crystal structure, so if an external force is applied to it, voltage is generated on the surface; if voltage is impressed to the crystal, displacement or force is generated to cause the volume variation. As shown in Fig. 2, the polarization direction P of the piezoelectric element 40 faces upward, but this is for illustrative purposes only. Because the volume variations of the piezoelectric element 40 take place after an electric field is created by an applied voltage to the upper and lower faces of the piezoelectric element 40, wiring (not shown) should be done for that. For instance, when (+) electrode is applied to the upper face and (-) electrode is applied to the lower face, the piezoelectric element 40 expands. On the contrary, when (-) electrode is applied to the upper face and (+) electrode is applied to the lower face, the piezoelectric element 40 contracts. The expansion or the contraction does not happen in the same way for every axis direction (x, y, and z), e.g., if expansion occurs in the x-y plane direction contraction occurs in the z-axis direction; if contraction occurs in the x-y plane direction expansion occurs in the z-axis direction. Through this wiring, when a sound signal (voltage) is applied, the piezoelectric element undergoes transformation by expanding or contracting in response to the sound signal.

[46] Referring to Fig. 3, if a sound signal is input to the sound converting apparatus and if the upper face is occupied by (+) electrode and the lower face is occupied by (-) electrode, the piezoelectric element 40 contracts (that is, it contracts in the x-y plane direction and expands in the z-axis direction). When this occurs, the attachment portion 31 also contracts and the dome portion 32 is stretched over by the contracted attachment portion 31.

[47] As the dome portion 32 expands and contracts repeatedly as depicted in Figs. 3 and

4, sound corresponding to the sound signal is produced and radiated above the diaphragm 30.

[48] The piezoelectric element 40 may be composed of plural layers of a piezoelectric element, or a single layer as illustrated in Fig. 2. In case of the former, the polarization directions of neighboring piezoelectric element layers should be opposite to let the layers expand or contract in the same direction. Moreover, as is done in Figs. 3 and 4, wiring work can be done properly to cause contraction in the x-y plane direction while expansion occurs in the z-axis direction, and to cause expansion in the x-y plane direction while contraction occurs in the z-axis direction.

[49] Fig. 6 through Fig. 9 are cross-sectional views of a sound converting apparatus, in accordance with a second embodiment of the present invention. The sound converting apparatus of Fig. 6 differs from that of Fig. 2 by employing two piezoelectric elements 42 and 44. As shown in Fig. 6, the piezoelectric elements 42 and 44 having the same polarization direction are layered on the bottom face of the diaphragm 30.

[50] Fig. 7 shows wiring required for application of a sound signal to the sound converting apparatus of Fig. 6. A voltage is applied to the upper face of the piezoelectric element 42 and to the lower face of the piezoelectric element 44, and a voltage is applied to the interface between the lower face of the piezoelectric element 42 and the upper face of the piezoelectric element 44. That is, a sound signal is applied through nodes A and B.

[51] Fig. 8 illustrates a state where a sound signal is applied to the sound converting apparatus of Fig. 6. In this case, (+) is applied to node A and (-) electrode is applied to node B, so the piezoelectric element 42 expands and the piezoelectric element 44 contracts. Accordingly, the attachment portion 31 is expanded and the dome portion 32 is folded. Because of the expanded piezoelectric element 42 and the contracted piezoelectric element 44, the diaphragm 30 is convexly bent upward.

[52] Fig. 9 illustrates a state where a sound signal is applied to the sound converting apparatus of Fig. 6. In this case, (-) is applied to node A and (+) electrode is applied to node B, so the piezoelectric element 42 contracts and the piezoelectric element 44 expands. Accordingly, the attachment portion 31 is contracted and the dome portion 32 is stretched out. Because of the contracted piezoelectric element 42 and the expanded piezoelectric element 44, the diaphragm 30 is convexly bent downward.

[53] As behaviors shown in Fig. 8 and Fig. 9 are repeated alternately, sound corresponding to the sound signal is radiated toward the front of the diaphragm 30.

[54] Fig. 10 is a cross-sectional view of a sound converting apparatus, in accordance with a third embodiment of the present invention. The sound converting apparatus of this embodiment differs from the sound converting apparatus of Fig. 2 by a diaphragm 34. Referring to Fig. 10, the diaphragm 34 is formed into a dome shape with a structure composed of an outer attachment portion 34a placed at a diaphragm seat 24 of a frame 20 and an inner attachment portion 34b attached to a piezoelectric element 40 for support. Similar to the one shown in Fig. 5, the inner attachment portion 34b may be bonded to the upper face or the lateral face of the piezoelectric element 40. For the sound converting apparatus of Fig. 10 to radiate sound, contraction of the piezoelectric element 40 causes the diaphragm 34 to stretch over, while expansion of the piezoelectric element 40 causes the diaphragm 34 to fold.

[55] Fig. 11 is a cross-sectional view of a sound converting apparatus, in accordance with a fourth embodiment of the present invention. The sound converting apparatus of this embodiment differs from the sound converting apparatus of Fig. 2 by a piezoelectric element 44 and a support 50. Referring to Fig. 11, the piezoelectric element 44 is laminated to the lower face of the piezoelectric element 42 in a manner that they have the same polarization direction, and the support 50 is formed at the lower center area of the piezoelectric elements 42 and 44.

[56] A sound signal application method in Fig. 11 is similar to one used in Fig. 7, so the piezoelectric elements 42 and 44 are bent similarly to those of Figs. 8 and 9. The support 50 becomes an anchor point or a fixed point with respect to flexural displacements of the piezoelectric elements 42 and 44. In presence of the anchor point for all piezoelectric elements 42 and 44, both ends of the piezoelectric elements 42 and 44 vibrate with a greater displacement than that of Fig. 2. Since the diaphragm 30 vibrates with such an increased displacement, a better sound pressure can be generated.

[57] Fig. 12 is a cross-sectional view of a sound converting apparatus, in accordance with a fifth embodiment of the present invention.

[58] The sound converting apparatus of Fig. 12 includes a frame 20a with a recess 22a formed inside, a diaphragm 30 seated and supported at a diaphragm 24 formed at the frame 20a, piezoelectric elements 42a and 44a attached to the diaphragm 30, and piezoelectric elements 47a and 47b for covering a lower recess 23 inside the recess 22a.

[59] For the frame 20a, the diaphragm seat 24 attached by the diaphragm 30 is positioned near the recess 22a and the lower recess 23 is formed inside the recess 22a. A piezoelectric element support 26 is disposed near the lower recess 23 to support the piezoelectric elements 47a and 47b. A protector (not shown) can be seated on the diaphragm seat 24 from the top of the diaphragm 30.

[60] The diaphragm 30 is structurally and functionally identical with the diaphragm 30 of Fig. 2.

[61] The piezoelectric elements 42a and 44a have the same laminate structure as the piezoelectric elements 42 and 44 of Fig. 6. While the piezoelectric element 47a and the piezoelectric element 47b have the same polarization direction P, the piezoelectric element 47a and the piezoelectric element 42a have opposite polarization directions P. The piezoelectric elements 42a and 44a are connected to the piezoelectric elements 47a and 47b via a connection portion 50a positioned at the center between them. This connection portion 50a serves as an anchor point or a fixed point similar to the one in Fig. 11.

[62] Wrings are arranged such that the piezoelectric elements 47a and 47b convexly bend downward along the diaphragm if the piezoelectric elements 42a and 44a convexly bent upward along the diaphragm. Under the same wirings, if the piezoelectric elements 42a and 44a convexly bend downward along the diaphragm 30, the piezoelectric elements 47a and 47b convexly bend upward along the diaphragm 30.

[63] Fig. 13 is a cross-sectional view of a sound converting apparatus, in accordance with a sixth embodiment of the present invention, and Fig. 14 is a perspective view of the sound converting apparatus of Fig. 13. Fig. 13 is a cross-sectional view taken along line B-B' in Fig. 4.

[64] The sound converting apparatus of Fig. 13 includes a frame 20b having a recess

22a formed inside, diaphragms 36 seated and supported at diaphragm seats 24a formed at the frame 20b, an attachment portion 31a for connecting and supporting the diaphragms 36 from the inside of them, and piezoelectric elements 48a and 48b arranged inside the recess 22b, each having one side being supported by the lateral face of the frame 20b and the other side being attached to a connecting portion 52.

[65] For the frame 20b, the diaphragm seat 24a attached by the outer attachment portion

36a for the diaphragm 36 is positioned near the recess 22b and the inner space of the recess 22b serves as a resonance space. A protector (not shown) can be seated on the diaphragm seat 24a from the top of the diaphragm 36. The inner lateral face of the frame 20b has grooves, to which one ends of the piezoelectric elements 48a and 48b can be inserted and supported. Optionally, one ends of the piezoelectric elements 48a and 48b may be anchored by a support (not shown) formed at the bottom of the recess 22b.

[66] The diaphragm 36 has an opening inside, and has a dome shaped cross-section.

Further, the diaphragm 36 includes the (outer) attachment portion 36a and an attachment portion 36b connected to the attachment portion 3 Ia functioning as a connector. Similar to the diaphragm 30 of Fig. 2, the diaphragm 36 may be integrated with the attachment portion 31a.

[67] The piezoelectric elements 48a and 48b have the same polarization direction P, and their one ends are fixedly mounted. That is, a fixed point for each piezoelectric element 48a or 48b is formed. For the application of a sound signal, therefore, wirings are arranged such that the piezoelectric elements 48a and 48b bend as shown in Fig. 6, while a part connected to the connecting portion 52 vibrates in a vertical direction. The vertical vibrations of the piezoelectric elements 48a and 48b cause the connecting portion 52 and the attachment portion 31a to vibrate in a vertical direction, and the diaphragm 36 is either stretched over or folded accordingly so as to produce sound.

[68] Fig. 15 is a cross-sectional view of a sound converting apparatus, in accordance with a seventh embodiment of the present invention. Referring to Fig. 15, the sound converting apparatus includes a frame 20c having a recess 22c formed inside, a diaphragm 30b seated and supported at a diaphragm seat 24b formed at the frame 20c, and piezoelectric elements 49a and 49b fixedly attached to an attachment portion 31b of the diaphragm 30b by means of a connecting portion 54.

[69] For the frame 20c, the diaphragm seat 24b attached by the diaphragm 30b is positioned near the recess 22c and a lower recess 23a is formed inside the recess 22c. A piezoelectric element support 26b is disposed near the lower recess 23a to support the piezoelectric elements 49a and 49b. A protector (not shown) can be seated on the diaphragm seat 24b from the top of the diaphragm 30b.

[70] The diaphragm 30b includes an attachment portion 37a seated and connected to the diaphragm seat 24a of the frame, an inner attachment portion 31a to which a connecting portion 54 is adhered, and a dome portion 37 which is either stretched out or folded depending on the bending motions of the piezoelectric elements 49a and 49b. In the presence of the connecting portion 54, the diaphragm 30b is fixed at a predetermined distance away from the piezoelectric elements 49a and 49b so that the bending motions of the piezoelectric elements 49a and 49b are transmitted through the inner attachment portion 31a, causing the dome portion to stretch over or fold continuously or similtaneously.

[71] Meanwhile, wiring of the piezoelectric elements 49a and 49b and the application of a sound signal are done in the same manner as those of the sound converting apparatus of Fig. 7.

[72] The present invention has been described in detail with reference to the embodiments and the attached drawings. However, the scope of the present invention is not limited to the embodiments and the drawings, but defined by the appended claims.

Claims

[1] A sound converting apparatus, comprising: a piezoelectric element; a diaphragm having an inner attachment portion to be attached to the piezoelectric element, and a vibrating portion being stretched or folded according to the transformation of the piezoelectric element; and a frame having a recess and a diaphragm seat positioned near the recess, to which an outer attachment portion of the diaphragm is attached.

[2] The sound converting apparatus of claim 1, wherein the inner attachment portion is adhered to an upper or lateral face of the piezoelectric element.

[3] The sound converting apparatus of claim 2, wherein the inner attachment portion is adhered circumferentially surrounding the upper or lateral face of the piezoelectric element.

[4] The sound converting apparatus of claim 1, wherein the piezoelectric element includes at least a first and a second piezoelectric element layer, having the same polarization direction for each, or opposite polarization directions.

[5] The sound converting apparatus of claim 1 or claim 4, wherein the frame has a support inside the recess, for supporting the piezoelectric element.

[6] The sound converting apparatus of claim 5, wherein the support is connected to the center of the piezoelectric element.

[7] The sound converting apparatus of claim 4, further comprising: a second piezoelectric element underneath the piezoelectric element, a connecting portion for connecting the piezoelectric element with the second piezoelectric element, and a second support for supporting the second piezoelectric element inside the recess.

[8] The sound converting apparatus of claim 1 , wherein the recess includes a second recess underneath the second piezoelectric element.

[9] The sound converting apparatus of claim 1 , wherein the vibrating portion is formed into a dome shape between the inner attachment portion and the outer attachment portion.

[10] The sound converting apparatus of claim 9, wherein an apex of the dome portion is relatively thinner than the periphery of the dome portion.

[11] A sound converting apparatus, comprising: a piezoelectric element; a diaphragm having a piezoelectric attachment portion to be attached to one end of the piezoelectric element, and a vibrating portion being stretched or folded according to the transformation of the piezoelectric element; and a frame having a recess for housing the piezoelectric element and the diaphragm therein, a diaphragm seat attached by a frame attachment portion of the diaphragm on the periphery of the recess, and a support attached by the other end of the piezoelectric element.

[12] The sound converting apparatus of claim 11, wherein the piezoelectric element attachment portion is formed at the center of the diaphragm, and the vibrating portion is formed into a dome shape on the periphery of the diaphragm.

[13] The sound converting apparatus of claim 11, wherein the support is formed at a lateral face of the recess, into which the other end of the piezoelectric element is inserted and housed.

[14] The sound converting apparatus of claim 11, wherein the piezoelectric element includes at least first and second piezoelectric element layers, having the same polarization direction for each.

[15] A sound converting apparatus, comprising: a piezoelectric element having a first piezoelectric element layer and a second piezoelectric element layer, having the same polarization direction for each; a diaphragm having a connecting portion to be connected to one side of the piezoelectric element, and a vibrating portion surrounding the piezoelectric element connecting portion and being stretched or folded according to the transformation of the piezoelectric element; and a frame having a recess for housing the piezoelectric element and the diaphragm therein, a diaphragm seat attached by a frame attachment portion of the diaphragm on the periphery of the recess, and a support for supporting the piezoelectric element inside the recess.

[16] The sound converting apparatus of claim 15, wherein the vibrating portion is formed into a dome shape.

[17] The sound converting apparatus of claim 15, wherein the connecting portion of the diaphragm is connected to an upper face of the piezoelectric element.

[18] The sound converting apparatus of claim 15 or claim 16, wherein the connecting portion of the diaphragm separates the diaphragm and the piezoelectric element by a predetermined distance from each other.

[19] The sound converting apparatus of claim 15, wherein the recess has a second recess underneath the piezoelectric element.