KR20140083912A - Piezoelectric device and piezoelectric speaker having the same - Google Patents

Abstract

In the present invention, suggested are a piezoelectric device and a piezoelectric speaker including the same. The piezoelectric device includes a vibration inducing layer which is not polarized and at least two piezoelectric layers which are formed on the upper and lower sides of the vibration inducing layer and are polarized and laminated in a thickness direction. The piezoelectric layers are laminated such that the polarization directions are opposite to each other.

Description

TECHNICAL FIELD [0001] The present invention relates to a piezoelectric device,

The present invention relates to a piezoelectric speaker, and more particularly, to a piezoelectric speaker using a piezoelectric element capable of improving output and sound pressure.

Generally, a piezoelectric element is a device having a characteristic capable of changing electric energy and mechanical energy with each other. That is, a piezoelectric element generates a voltage when a pressure is applied (a piezoelectric effect), and when a voltage is applied, the volume or length of the piezoelectric element is increased or decreased due to a change in pressure inside the piezoelectric element. The piezoelectric element is composed of a piezoelectric layer and an electrode provided on the piezoelectric layer, and the pressure changes according to the voltage applied to the piezoelectric layer through the electrode.

By using these piezoelectric elements, it is possible to manufacture omnidirectional parts such as piezoelectric speaker and vibration device. In the meantime, the piezoelectric speaker is a part that generates a sound of a desired frequency band by acoustically converting the mechanical movement of the piezoelectric element by the diaphragm. Such a piezoelectric speaker is advantageous in that it is thin, light and consumes less power than a conventional dynamic speaker, and thus can be used in electronic devices such as a smart phone requiring a compact, thin and light weight. The piezoelectric speaker includes a piezoelectric element and a diaphragm formed larger than the piezoelectric element and bonded to one surface of the piezoelectric element to amplify vibration generated in the piezoelectric element. The acoustic characteristics of these piezoelectric loudspeakers are judged to be the sound pressure of each frequency, and the sound pressure of each frequency may vary according to the material and properties of the diaphragm. A piezoelectric speaker with a good characteristic means that it has a high output, a high frequency sound pressure, a flat shape, and a wide sound range. Korean Patent Laid-Open Publication No. 2011-0064369 discloses a piezoelectric speaker capable of minimizing distortion of a sound by preventing a standing wave generated due to structural symmetry by attaching the piezoelectric element and the diaphragm so that they have a tilted structure that is horizontally offset .

The diaphragm applied to the piezoelectric speaker is made of a metal material, a polymer material, pulp or the like. In the case of a metal-based diaphragm, there is an advantage of increasing the output for converting the vibration of the piezoelectric element into a sound wave because of its excellent elasticity and high transmission speed. However, only a narrow band is implemented, a sound pressure- There is a drawback that the weight is heavy. On the other hand, in the case of a polymer diaphragm or a pulp diaphragm, there is a disadvantage in that the sound pressure is lower and the output is lower than that of the metal diaphragm due to lack of elasticity. However, the sound pressure drop phenomenon at the lowest resonance frequency and frequency band There is an excellent advantage.

Therefore, when the polymer diaphragm or the pulp diaphragm is used, it is necessary to overcome the disadvantage that the output for converting the vibration of the piezoelectric element into a sound wave is lowered.

The present invention provides a piezoelectric speaker capable of improving output and sound pressure.

The present invention provides a piezoelectric speaker in which a piezoelectric element capable of improving output and sound pressure is used together with a polymer diaphragm or a pulp diaphragm.

A piezoelectric device according to one aspect of the present invention includes a non-polarized vibration inducing layer; And at least two piezoelectric layers provided on upper and lower portions of the vibration inducing layer and polarized and laminated in the thickness direction, respectively, and each of the piezoelectric layers is laminated such that the polarization directions thereof are opposite to each other.

The vibration inducing layer and the piezoelectric layer are formed of the same material.

Electrodes are formed between the vibration inducing layer and the piezoelectric layers, and the electrodes to which the same polarity voltage is applied are connected through at least one via plug formed in a predetermined region of the vibration inducing layer and the piezoelectric layers .

Electrodes are formed between the vibration inducing layer and the piezoelectric layers, and the electrodes are exposed to two opposing sides of the laminated piezoelectric layers, and are supplied with voltages of different polarities

The piezoelectric element according to another aspect of the present invention includes at least two piezoelectric layers that are polarized and laminated in the thickness direction, and the piezoelectric layer positioned at the center of the piezoelectric layers is thicker than the other piezoelectric layers, The piezoelectric layers provided on the upper and lower sides are laminated so that their polarization directions are opposite to each other.

Electrodes are formed between the piezoelectric layers, and the electrodes to which the same polarity voltage is applied are connected through at least one via plug formed in a predetermined region of the piezoelectric layers.

According to another aspect of the present invention, there is provided a piezoelectric speaker comprising: a diaphragm; A piezoelectric element provided on the diaphragm; And a case accommodating the diaphragm and the piezoelectric element therein, wherein the piezoelectric element comprises: a non-polarized vibration inducing layer; and a plurality of piezoelectric ceramic layers provided on the upper and lower portions of the vibration inducing layer, The piezoelectric layer includes two or more piezoelectric layers, and the piezoelectric layers are laminated so that their polarization directions are opposite to each other.

The diaphragm is formed of a polymer-based or pulp-based material.

An adhesive tape provided between the piezoelectric element and the vibration plate, and an adhesive provided on at least one side of the piezoelectric element.

According to another aspect of the present invention, there is provided a piezoelectric speaker comprising: a piezoelectric element; And a case in which the side surface of the piezoelectric element is bonded to the inner side to receive the piezoelectric element, wherein the piezoelectric element includes at least two piezoelectric layers that are polarized and laminated in the thickness direction, The piezoelectric layer positioned at the center is thicker than the other piezoelectric layers, and the piezoelectric layers provided at the upper and lower portions of the thick piezoelectric layer are laminated so that their polarization directions are opposite to each other.

The present invention is characterized in that a plurality of piezoelectric layers polarized in the thickness direction are provided on upper and lower portions of a non-polarized vibration inducing layer, and when the plurality of polarized piezoelectric layers are expanded and contracted, expansion and contraction are amplified by the vibration inducing layer A characteristic similar to the vibration of the diaphragm is provided without the diaphragm of the diaphragm. When such a piezoelectric element is brought into contact with a polymer-based or pulp-based diaphragm to manufacture a piezoelectric speaker, the diaphragm makes a secondary vibration of the primary vibration generated in the piezoelectric element, so that the vibration can be further amplified.

Therefore, even if a polymer-based or pulp-based diaphragm is used as the diaphragm, sound pressure and output can be further improved as compared with the conventional art.

1 is a cross-sectional view of a piezoelectric element according to an embodiment of the present invention;
2 is a cross-sectional view of a piezoelectric device according to another embodiment of the present invention;
3 is a cross-sectional view of a piezoelectric device according to another embodiment of the present invention.
4 and 5 are an exploded perspective view and an assembled cross-sectional view of a piezoelectric speaker with a piezoelectric element according to an embodiment of the present invention;
6 is a cross-sectional view of a piezoelectric speaker in accordance with another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of other various forms of implementation, and that these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know completely.

1 is a cross-sectional view of a piezoelectric element according to an embodiment of the present invention.

1, a piezoelectric device 100 according to an embodiment of the present invention includes first to third piezoelectric layers 110, 120, and 130 that are polarized and laminated in a thickness direction, a third piezoelectric layer 130, And a fourth to sixth piezoelectric layers 150, 160, and 170 that are provided under the vibration inducing layer 140 and are polarized and laminated in the thickness direction. That is, in the piezoelectric element 100 according to an embodiment of the present invention, the first to third piezoelectric layers 110, 120, and 130 are provided on the vibration inducing layer 140, To sixth piezoelectric layers 150, 160, and 170 are provided. The vibration inducing layer 140 and the plurality of piezoelectric layers 110, 120, 130, 150, 160 and 170 may be formed of the same material. For example, PZT (Pb, Zr, Ti), NKN , K, Nb) and BNT (Bi, Na, Ti) based piezoelectric materials.

The first to third piezoelectric layers 110, 120, and 130 may be formed as a thin plate having a substantially circular or rectangular shape as a means having a piezoelectric property by poling in the thickness direction. The shapes of the first to third piezoelectric layers 110, 120 and 130 are not limited to the illustrated embodiments and may be variously changed if piezoelectric characteristics applicable to the piezoelectric speaker are formed. The first to third piezoelectric layers 110, 120 and 130 are stacked so that their polarization directions are opposite to each other. For example, the first and third piezoelectric layers 110 and 130 are polarized in an opposite direction to the vibration inducing layer 140, that is, the upper direction, and the second piezoelectric layer 120 is polarized in the direction of the vibration inducing layer 140 That is, in the downward direction. The first piezoelectric layer 110 has a first electrode 111 formed on the upper surface thereof and a first b electrode 113 formed on the lower surface thereof and polarized in the direction of the first electrode 113 from the first b electrode 113 have. The second piezoelectric layer 120 has a second b electrode 123 formed on its top surface and is bonded to the first b electrode 113 of the first piezoelectric layer 110. The second electrode 121 is formed on the bottom surface of the second piezoelectric layer 120, And may be polarized in the direction of the 2a electrode 121 from the 2b electrode 123. At this time, the first and second electrodes 113 and 123 may be integrally formed. A third electrode 131 is formed on the upper surface of the third piezoelectric layer 130 and bonded to the second electrode 121 of the second piezoelectric layer 120. A third electrode 133 is formed on the lower surface of the third piezoelectric layer 130, The third electrode 131 may be polarized in the direction of the third electrode 131. At this time, the 2a electrode 121 and the 3a electrode 131 may be integrally formed.

The vibration inducing layer 140 does not polarize in the thickness direction and does not have piezoelectric characteristics. It induces and amplifies vibration in the third and fourth piezoelectric layers 130 and 150, or acts as a direct diaphragm . A pair of electrodes 143 electrically connected to the third electrode 133 and the fourth electrode 153 are formed on the upper surface and the lower surface of the vibration inducing layer 140, respectively. At this time, the electrode 143 and the third electrode 133 formed on the upper surface of the vibration inducing layer 140 may be integrally formed.

The fourth to sixth piezoelectric layers 150, 160, and 170 may be formed of a substantially circular or rectangular thin plate as a means having a piezoelectric characteristic by poling in the thickness direction. The shape of the fourth to sixth piezoelectric layers 150, 160, and 170 may be variously changed without being limited to the illustrated embodiment if piezoelectric characteristics applicable to the piezoelectric speaker are formed. The fourth to sixth piezoelectric layers 150, 160, and 170 are stacked so that their polarization directions are opposite to each other. For example, the fourth and sixth piezoelectric layers 150 and 170 are polarized in the opposite direction to the vibration inducing layer 140, that is, the downward direction, and the fifth piezoelectric layer 160 is polarized in the direction of the vibration inducing layer 140 That is, in the upward direction. The fourth piezoelectric layer 150 includes a fourth electrode 153 formed on the upper surface thereof and bonded to the electrode 143 of the vibration inducing layer 140 and a fourth electrode 151 formed on the lower surface of the fourth piezoelectric layer 150, 143 in the direction of the fourth electrode 141. The electrode 143 formed on the lower surface of the vibration inducing layer 140 may be formed integrally with the fourth electrode 153 of the fourth piezoelectric layer 150. The fifth piezoelectric layer 160 has a fifth electrode 151 formed on its top surface and bonded to the fourth electrode 151 of the fourth piezoelectric layer 120 and a fifth electrode 153 formed on the bottom surface thereof, 5b electrode 153 to the 5a electrode 151 direction. At this time, the fourth electrode 151 and the fifth electrode 161 may be integrally formed. The sixth piezoelectric layer 170 has a sixth electrode 173 formed on the top surface thereof and bonded to the fifth electrode 163 of the fifth piezoelectric layer 160 and a sixth electrode 171 formed on the bottom surface thereof. 6b electrode 173 to the sixth electrode 171. In this case, At this time, the 5b electrode 163 and the 6b electrode 173 can be integrally formed.

The first, second, third, fourth, fifth and sixth electrodes 111, 121, 131, 151 and 151 of the first through sixth piezoelectric layers 110, 120, 130, 161, and 171 are electrically connected to each other and the first, second, third, fourth, fifth, and sixth electrodes 113, 123, 133, 153, 163, and 173 are electrically connected to each other. The first, second, third, fourth, fifth and sixth electrodes 111, 121, 131, 151, 161, 171 and first, second, 6b electrodes 113, 123, 133, 153, 163, and 173 are insulated from each other. The first, second, third, fourth, fifth and sixth electrodes 111, 121, 131, 151, 161 and 161 of the first, second, third, and fourth piezoelectric layers 110, A first via hole formed to penetrate the first through sixth piezoelectric layers 110, 120, 130, 150, 160, and 170 and the vibration inducing layer 140 to be electrically connected to each other, One via plug 180 is formed. The first, the second, the third, the fourth, the fifth and the sixth electrodes 113, 123, 133 and 153 of the first to sixth piezoelectric layers 110, 120, 130, 150, 163 and 173 are electrically connected to each other, a second via hole in which a conductive material is buried in a second via hole formed to pass through the second to fifth piezoelectric layers 120, 130, 150, and 160 and the vibration inducing layer 140, A plug 190 is formed. In order to prevent short-circuiting between the a-electrodes and the b-electrodes, the first via plug 180 of the piezoelectric layers 110 to 170 is formed in the region of the first via plug 180 in the first, second, third, fourth, fifth, 3a, 4a and 5a electrodes 121, 131, 151, and 151 are formed in the region where the second via plugs 190 are formed without the electrodes 611, 6b, 113, 123, 133, 153, 163, 161 are not formed.

In this piezoelectric element 100, the (+) pole of the power supply means 10 is connected to the first electrode 111, for example, and the (-) pole is connected to the sixth electrode 173, . That is, positive power is applied to the electrodes 1a, 2a, 3a, 4a, 5a and 6a electrodes 111, 121, 131, 151, 161 and 171, (-) power is applied to the first, fourth, fifth, and sixth electrodes 113, 123, 133, 153, 163, and 173.

2 is a cross-sectional view of a piezoelectric element according to another embodiment of the present invention.

2, the piezoelectric device 100 according to another embodiment of the present invention includes first to third piezoelectric layers 110, 120, and 130 that are polarized and laminated in the thickness direction, a third piezoelectric layer 130, And a fourth to sixth piezoelectric layers 150, 160, and 170 that are provided under the vibration inducing layer 140 and are polarized and laminated in the thickness direction. The vibration inducing layer 140 and the plurality of piezoelectric layers 110, 120, 130, 150, 160 and 170 may be formed of the same material. For example, PZT (Pb, Zr, Ti), NKN , K, Nb) and BNT (Bi, Na, Ti) based piezoelectric materials. The piezoelectric element 100 includes a plurality of internal electrodes 112, 122, 132, 152, 162, and 162 formed between the piezoelectric layers 110 to 170 in a laminated body in which a plurality of piezoelectric layers 110 to 170 are stacked. 172 are provided. The internal electrodes 112, 122, 132, 152, 162, 172 are alternately exposed to both sides of the laminate. A first end face electrode 182 is formed on one side of the laminate body and connected to the internal electrodes 122, 132, 152, 172 exposed on one side face, and a second end face electrode 182 is formed on the other side face of the laminate body. A first upper surface electrode 186a connected to the first end surface electrode 182 and a second upper surface electrode 182 connected to the upper surface of the laminate body, A first lower electrode 188a connected to the first end face electrode 182 and a second upper face electrode 186b connected to the second end face electrode 184 are formed on the lower face of the laminate body, A second lower surface electrode 188b connected to the electrode 184 is formed apart from the first upper surface electrode 186a and a terminal for external connection is formed on the first upper surface electrode 186a and the second upper surface electrode 186b.

The piezoelectric element according to another embodiment of the present invention has the same structure as the piezoelectric element according to an embodiment of the present invention but differs in that the internal electrodes are exposed to the outside to be connected to the end electrode. That is, in the piezoelectric element according to the embodiment of the present invention, the first and second via holes are formed so as to penetrate the plurality of piezoelectric layers, and the electrodes are connected to each other through the via hole. However, in the piezoelectric element according to another embodiment of the present invention, The inner electrodes 112, 122, 132, 152, 162 and 172 are alternately exposed to both sides of the laminate and the first and second end electrodes 182 and 184 are exposed from one side surface and the other side of the laminate, 112, 122, 132, 152, 162, 172, respectively.

As described above, the piezoelectric element according to one embodiment of the present invention and the other embodiment of the present invention includes a non-polarized vibration inducing layer 140 provided at a central portion, a plurality of piezoelectric layers 110 , 120, 130, 150, 160, 170). Accordingly, when voltage is applied to the plurality of polarized piezoelectric layers 110, 120, 130, 150, 160, 170 and expanded and contracted, expansion and contraction are amplified by the vibration-inducing ceramic plate 140. That is, the vibration inducing layer 140 serves to amplify the vibration, so that the vibration inducing layer 140 exhibits characteristics similar to those of being vibrated by the vibration plate without providing the vibration plate.

3 is a cross-sectional view of a piezoelectric device according to another embodiment of the present invention.

3, a piezoelectric device 100 according to another embodiment of the present invention includes first through fifth piezoelectric layers 110, 120, 130, 150, and 160 which are polarized and laminated in a thickness direction, The thickness of the third piezoelectric layer 130 is greater than the thickness of the first, second, fourth, and fifth piezoelectric layers 110, 120, 160, and 160. The first to fifth piezoelectric layers 110, 120, 130, 140 and 150 may be formed of the same material. For example, PZT (Pb, Zr, Ti), NKN (Na, K, BNT (Bi, Na, Ti) based piezoelectric material.

The configuration and shape of the first to fifth piezoelectric layers 110, 120, 130, 150 and 160 are the same as those of the first to fifth piezoelectric layers 110, 120, 130, 150, . However, it is preferable that the thickness of the third piezoelectric layer 130 is thicker than the thickness of the first, second, fourth, and fifth piezoelectric layers 110, 120, 150, and 160 in this embodiment. As the thickness of the third piezoelectric layer 130 is made thicker than the thicknesses of the other piezoelectric layers 110, 120, 150 and 160, the piezoelectric layers 110, 120 and 150 having different polarization states of the third piezoelectric layer 130 , 160), thereby causing a polarization vibration due to the polarization difference. Unexplained reference numerals 180 and 190 are via plugs.

As described above, according to another embodiment of the present invention, the piezoelectric layer 130 having a thick thickness is provided at the center and the piezoelectric layers 110 having a thickness thinner than that of the third piezoelectric layer 130 , 120, 140, 150) are provided at the upper and lower portions thereof. Accordingly, the voltage is applied to the polarized piezoelectric layers 110, 120, 130, 140, and 150 to expand and contract, and the expansion and contraction is amplified by the third piezoelectric layer 130 at the center. That is, the third piezoelectric layer 130 having a large thickness functions to amplify the vibration, so that the piezoelectric layer 130 exhibits characteristics similar to the vibration of the diaphragm without providing the diaphragm.

4 and 5 are an exploded perspective view and an assembled cross-sectional view of a piezoelectric speaker with a piezoelectric device according to an embodiment of the present invention. Here, the piezoelectric element will be described taking the piezoelectric element described with reference to Fig. 2 as an example.

4 and 5, a piezoelectric speaker according to an embodiment of the present invention includes a rectangular piezoelectric element 100, a diaphragm 200 for increasing the vibration of the piezoelectric element 100, An adhesive tape 300 for adhering the piezoelectric element 100 and a case 400 for housing the piezoelectric element 100 attached to the diaphragm 200. [ The piezoelectric device 100 further includes an adhesive 500 provided on a side surface of the piezoelectric device 100 and adhering the piezoelectric device 100 to the adhesive tape 300.

The piezoelectric element 100 includes first to third piezoelectric layers 110, 120 and 130 which are polarized and laminated in the thickness direction as shown in FIG. 2, and first to third piezoelectric layers 110, 120 and 130 which are provided under the third piezoelectric layer 130 A vibration inducing layer 140 and fourth to sixth piezoelectric layers 150, 160 and 170 which are provided under the vibration inducing layer 140 and are polarized and laminated in the thickness direction. The piezoelectric element 100 includes a plurality of internal electrodes 112, 122, 132, 152, 162, and 162 formed between the piezoelectric layers 110 to 170 in a laminated body in which a plurality of piezoelectric layers 110 to 170 are stacked. 172 are provided. The internal electrodes 112, 122, 132, 152, 162, 172 are alternately exposed to both sides of the laminate. A first end face electrode 182 is formed on one side of the laminate body and connected to the internal electrodes 122, 132, 152, 172 exposed on one side face, and a second end face electrode 182 is formed on the other side face of the laminate body. A first upper surface electrode 186a connected to the first end surface electrode 182 and a second upper surface electrode 182 connected to the upper surface of the laminate body, A first lower electrode 188a connected to the first end face electrode 182 and a second upper face electrode 186b connected to the second end face electrode 184 are formed on the lower face of the laminate body, A second lower electrode 188b connected to the electrode 184 is spaced apart and a terminal 600 for external connection is formed on the first upper electrode 186a and the second upper electrode 186b. That is, power can be supplied from the outside through the terminal 600. [

The diaphragm 200 may be made of a polymer-based material or a pulp-based material. For example, the diaphragm 200 can use a resin film, and a material having a Young's modulus of 1 MPa to 10 GPa and a large loss coefficient such as an ethylene propylene rubber system or a styrene butadiene rubber system can be used. The diaphragm 200 is provided in a rectangular shape larger than the piezoelectric element 100 and the piezoelectric element 100 is bonded to the upper surface of the diaphragm 200. Further, the edge of the diaphragm 200 can be held at the edge of the case 400 as shown in Fig. That is, the diaphragm 200 is provided with a piezoelectric element 100 bonded to the center of the diaphragm 200 in a space inside the case 400 and an edge positioned between the edges of the lower case 410 and the upper case 420, Can be fixed.

An adhesive tape 300 is provided on the diaphragm 200 and the piezoelectric element 100 is attached to the diaphragm 200 by the adhesive tape 300. The adhesive tape 300 may be an adhesive material such as a rubber, acrylic, or silicone adhesive. On the other hand, the adhesive tape 300 may have the same shape and size as the diaphragm 200, and may have the same shape and size as the piezoelectric element 100. The edge of the adhesive tape 300 may be sandwiched between the edges of the case 400 together with the edge of the diaphragm 200 when the adhesive tape 300 is provided in the same size as the diaphragm 200, for example.

On the other hand, the adhesive 500 may be applied to at least one side of the piezoelectric element 100. For example, the adhesive 500 may be applied to the side surface from the edge of the upper surface of the piezoelectric element 100, and may be applied to all the sides from the edge of the four upper surfaces of the piezoelectric element 100. Further, the adhesive 500 may be provided at least partially on at least one side of the piezoelectric element 100. That is, the adhesive 500 may be partially applied to the side surface of the piezoelectric element 100, or may be applied as a whole. The adhesive 500 is a reinforcing agent for preventing peeling from occurring at the interface between the side surface of the piezoelectric element 100 and the adhesive tape 300. As the adhesive 500, it is preferable to use a thermosetting adhesive having a low Young's modulus such as urethane or silicone which does not restrict the displacement of the piezoelectric element 100 as much as possible.

The case 400 is provided with a predetermined space therein to receive the piezoelectric element 100 and the diaphragm 200 and the like. The case 400 may include an upper case 410 provided on the upper side of the piezoelectric element 100 and a lower case 420 provided on the lower side of the diaphragm 200. The upper and lower cases 410 and 420 sandwich the edges of the diaphragm 200 so that the piezoelectric element 100 is positioned inside. The case 400 is spaced apart from the upper surface of the piezoelectric element 100 and the lower surface of the diaphragm 200 by a predetermined space. The space between the piezoelectric element 100 and the diaphragm 200 in the case 400 becomes a vibration space of the piezoelectric element 100. [ To this end, the upper case 410 includes a first plane portion provided along the edge of the diaphragm 200, a vertical portion extending upward from the inner side of the first plane portion and spaced apart from the side surface of the piezoelectric element 100 by a predetermined distance, And a second plane portion facing the upper surface of the element 100 and provided between the vertical portions. At this time, the space between the piezoelectric element 100 and the second plane portion is determined according to the height of the vertical portion. Further, the lower case 420 may be provided in the same shape as the upper case 410 so as to face the upper case 410. That is, it includes a first plane portion provided along the edge of the diaphragm 200, a vertical portion extending downward from the inside of the first plane portion, and a second plane portion provided between the bottom portion of the diaphragm 200 and the vertical portion can do. Meanwhile, a plurality of sound insulation holes 412 may be formed in a predetermined area of the upper case 410, for example, a vertical portion. The soundproofing hole 412 may be formed in a circular shape, or may be formed in various shapes such as a quadrangle, an ellipse, and the like. Also, a sound-proof hole 422 may be formed in a predetermined area of the lower case 420. The sound-proofing hole 422 may be formed in the second plane portion of the lower case 420, for example. The second planar portion of the lower case 420 is spaced apart from the second planar portion of the piezoelectric element 100 so that the second planar portion of the upper case 410 faces the piezoelectric element 100, It may be smaller than the distance between the upper case 410 and the upper case 410. [

As described above, when the piezoelectric device according to the embodiments of the present invention is brought into contact with the polymer-based or pulp-based diaphragm to manufacture the piezoelectric speaker, the diaphragm vibrates the primary vibration generated by the piezoelectric device secondarily, . Therefore, even if a polymer-based or pulp-based diaphragm is used as the diaphragm, sound pressure and output can be further improved as compared with the conventional art.

6 is a schematic cross-sectional view of a piezoelectric speaker according to another embodiment of the present invention. The side surface of the piezoelectric element 100 is fixed to the inside of the case 410 or 420 by the adhesive 500 as shown in FIG. That is, the piezoelectric element 100 according to the embodiments of the present invention shown in FIGS. 1 to 3 is provided in the case 410, 420 without a diaphragm or the like and spaced apart from the sides of the cases 410, 420, The piezoelectric element 100 is fixed to the inside of the case 410, 420 by the adhesive 500. When the piezoelectric speaker 100 is made to be fixed to the inner surface of the case 400 according to the embodiments of the present invention, the piezoelectric device 100 itself vibrates, and thus, without using a separate diaphragm, A large vibration can be generated.

Although the technical idea of the present invention has been specifically described according to the above embodiments, it should be noted that the above embodiments are for explanation purposes only and not for the purpose of limitation. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention.

100: Piezoelectric elements 110, 120, 130, 150, 160, 170:
140: vibration inducing layer 200: diaphragm
300: adhesive tape 400: case
500: adhesive 600: terminal

Claims (10)

A non-polarized vibration inducing layer;
And at least two piezoelectric layers provided on the upper and lower portions of the vibration inducing layer and polarized and laminated in the thickness direction,
Wherein each of the piezoelectric layers is laminated such that the polarization directions thereof are opposite to each other.
The piezoelectric element according to claim 1, wherein the vibration inducing layer and the piezoelectric layer are formed of the same material.
The piezoelectric vibrator according to any one of claims 1 and 2, wherein electrodes are formed between the vibration inducing layer and the piezoelectric layers, and voltages of the same polarity are transmitted through at least one via plug formed in a predetermined region of the vibration inducing layer and the piezoelectric layers A piezoelectric element to which the electrodes to be applied are connected,
The piezoelectric vibrator according to claim 1 or 2, wherein electrodes are formed between the vibration inducing layer and the piezoelectric layers, respectively, and the electrodes are exposed to two opposing sides of the laminated piezoelectric layers, device.
At least two piezoelectric layers which are polarized and laminated in the thickness direction,
Wherein the piezoelectric layer positioned at the center of the piezoelectric layers is thicker than the other piezoelectric layers and the piezoelectric layers provided at the upper and lower portions of the thick piezoelectric layer are laminated so that their polarization directions are opposite to each other.
The piezoelectric element according to claim 5, wherein electrodes are formed between the piezoelectric layers, and the electrodes to which the voltages of the same polarity are applied through at least one via plug formed in a predetermined region of the piezoelectric layers are connected,
tympanum;
A piezoelectric element provided on the diaphragm; And
And a case accommodating the diaphragm and the piezoelectric element therein,
The piezoelectric element includes:
A non-polarized vibration inducing layer,
And at least two piezoelectric layers provided on the upper and lower portions of the vibration inducing layer and polarized and laminated in the thickness direction,
Wherein each of the piezoelectric layers is laminated such that polarization directions thereof are opposite to each other.
8. The piezoelectric speaker of claim 7, wherein the diaphragm is formed of a polymeric or pulp-based material.
The piezoelectric speaker according to claim 7 or 8, further comprising: an adhesive tape provided between the piezoelectric element and the diaphragm; and an adhesive provided on at least one side of the piezoelectric element.
A piezoelectric element; And
And a case having a side surface of the piezoelectric element adhered to an inner surface thereof to receive the piezoelectric element,
The piezoelectric element includes:
At least two piezoelectric layers which are polarized and laminated in the thickness direction,
Wherein the piezoelectric layer positioned at the center of the piezoelectric layers is thicker than the other piezoelectric layers, and the piezoelectric layers provided at the upper and lower portions of the thick piezoelectric layer are laminated so that their polarization directions are opposite to each other.

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