KR20120027915A - Piezoelcetric device and piezoelectric speaker usiong the same - Google Patents

Abstract

PURPOSE: A piezoelectric device and a piezoelectric speaker using the same are provided to bond piezoelectric devices of different resonant frequencies with both sides of a vibration plate, thereby obtaining uniform sound features. CONSTITUTION: A piezoelectric device(100) vibrates if a signal voltage is applied to an electrode. The piezoelectric device includes three-layered piezoelectric ceramic plates(110,120,130). The piezoelectric ceramic plates are stacked wherein the polarization directions of the piezoelectric ceramic plates opposite each other. First to third piezoelectric ceramic plates are successively stacked.

Description

Piezoelectric element and piezoelectric speaker using the same {Piezoelcetric device and Piezoelectric speaker usiong the same}

The present invention relates to a piezoelectric element and a piezoelectric speaker using the same, and more particularly, to a piezoelectric element and a piezoelectric speaker using the same to improve radial vibration characteristics and to flatten acoustic energy.

In general, a piezoelectric element refers to a device having a characteristic of changing electrical energy and mechanical energy from each other, and a piezoelectric speaker converts mechanical movement of the piezoelectric element into an acoustic wave by a diaphragm to generate sound of a desired frequency band. It is a representative product of acoustic components.

At this time, the piezoelectric element generates a voltage by the force applied to the piezoelectric ceramic, and the amount of the generated voltage varies depending on the strength of the piezoelectric element.

The general 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 the vibration generated in the piezoelectric element. The acoustic characteristics of the piezoelectric speaker may be determined as sound pressure for each frequency, and the sound pressure for each frequency may vary according to the material and physical properties of the diaphragm.

In general, a piezoelectric speaker having good characteristics means high output, high frequency sound pressure, and a flat shape and a wide sound range.

As the diaphragm applied to the piezoelectric speaker, metal materials, polymer materials, pulp, and the like are used.

In the case of the metal diaphragm, the metal has the advantage of increasing the output of converting the vibration of the piezoelectric element into sound waves due to its excellent elasticity and fast transfer speed, but only a narrow band is realized, and the sound pressure drop phenomenon occurs for each frequency and the thickness The disadvantage is thick and heavy weight.

On the other hand, polymer-based diaphragm or pulp-based diaphragm has a disadvantage in that the sound pressure is lower and the output is reduced compared to the metal-based diaphragm due to the lack of elasticity. There is an excellent advantage.

Therefore, when using a polymer diaphragm or a pulp diaphragm, there is a problem in that the output of converting the vibration of the piezoelectric element into sound waves has to be overcome.

Embodiments of the present invention provide a stacked piezoelectric element and a piezoelectric speaker using the same that can overcome the phenomenon that the output of acoustic energy is reduced when using a polymer-based or pulp-based diaphragm of the diaphragm of the piezoelectric speaker.

A piezoelectric element according to an embodiment of the present invention is a piezoelectric element that vibrates when a signal voltage is applied to an electrode, and includes at least three or more layers of piezoelectric ceramic plates that are polarized and stacked in the thickness direction, and each piezoelectric ceramic plate is polarized. It is characterized in that the laminated direction so that the directions are opposite to each other.

The piezoelectric ceramic plate is sequentially laminated in a downward direction on the first to third piezoelectric ceramic plates, a first external electrode is formed on an upper surface of the first piezoelectric ceramic plate, and a second on the lower surface of the third piezoelectric ceramic plate. An external electrode is formed, and a second internal electrode electrically connected to the second external electrode is formed between the first piezoelectric ceramic plate and the second piezoelectric ceramic plate, and between the second piezoelectric ceramic plate and the third ceramic plate. The first internal electrode electrically connected to the first external electrode is formed.

A third polarization-inducing ceramic plate which is not polarized is laminated on the lower surface of the third piezoelectric ceramic plate while being electrically connected by the second external electrode, and a third being electrically connected to the second external electrode on the lower surface of the vibration-inducing ceramic plate. An external electrode is formed.

The first external electrode and the first internal electrode are electrically connected to each other by a first via plug passing through the first and second piezoelectric ceramic plates, and the second and third external electrodes and the second internal electrode are connected to each other. And a second via plug penetrating the second and third piezoelectric ceramic plates and the vibration-inducing ceramic plate.

The third piezoelectric ceramic plate may have a thickness greater than that of the first and second piezoelectric ceramic plates.

The first external electrode and the first internal electrode are electrically connected by a first via plug passing through the first and second piezoelectric ceramic plates, and the second and second internal electrodes are connected to the second and third piezoelectric elements. And a second via plug penetrating the ceramic plate and the vibration-inducing ceramic plate.

Piezoelectric speaker according to an embodiment of the present invention and the diaphragm; And first and second piezoelectric elements bonded to both surfaces of the diaphragm, wherein the first and second piezoelectric elements are different in size from each other.

The first and second piezoelectric elements each include at least three or more layers of piezoelectric ceramic plates that are polarized and stacked in the thickness direction, and each of the piezoelectric ceramic plates is laminated so that the polarization directions are reverse to each other.

Each of the first and second piezoelectric elements may be sequentially laminated in a downward direction on the first to third piezoelectric ceramic plates, and each of the first and second piezoelectric ceramic plates may be selectively bonded to the third piezoelectric ceramic plate, or may be bonded to the third piezoelectric ceramic plate. The thickness of the piezoelectric ceramic plate is formed thicker than the thickness of the first and second piezoelectric ceramic plate.

The first and second piezoelectric elements are characterized in that the third piezoelectric ceramic plate formed thicker than the vibration-inducing ceramic plate or the first and second piezoelectric ceramic plates is bonded to the vibration plate.

The diaphragm is characterized in that it is a polymeric material or pulp.

According to the present invention, it is possible to improve the output of the piezoelectric element to improve the output degradation of the acoustic energy appearing in the polymer diaphragm or the pulp diaphragm.

In addition, displacement is generated in the diaphragm bonded to the laminated piezoelectric ceramic plate, so that a relatively large acoustic energy may be obtained than the conventional piezoelectric speaker.

In addition, piezoelectric elements having different resonance frequencies may be bonded to both surfaces of the diaphragm to compensate for portions in which sound pressure generated between resonance and resonance are inhibited, thereby obtaining uniform acoustic characteristics.

1 is a schematic cross-sectional view showing a piezoelectric element according to a first embodiment of the present invention,
2 is a schematic cross-sectional view showing a piezoelectric element according to a second embodiment of the present invention;
3 to 5 are schematic cross-sectional views showing piezoelectric speakers of various embodiments according to the present invention;
6 is a graph showing resonance frequencies for each frequency band of a piezoelectric speaker according to an exemplary embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know. Like numbers refer to like elements in the figures.

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

As shown in FIG. 1, the piezoelectric element 100 according to the first exemplary embodiment of the present invention includes first to third piezoelectric ceramic plates 110, 120, and 130 that are polarized and stacked in a thickness direction, and the third piezoelectric ceramic. And an unpolarized vibration-inducing ceramic plate 140 bonded to the plate 130.

The first piezoelectric ceramic plate to the third piezoelectric ceramic plate (110, 120, 130) is a means having a piezoelectric property by polarizing in the thickness direction, in this embodiment is formed of a thin plate of approximately circular or rectangular shape. The shape of the first piezoelectric ceramic plate to the third piezoelectric ceramic plate (110, 120, 130) is not limited to the present embodiment can be variously changed if the piezoelectric properties that can be applied to the piezoelectric speaker is formed.

The first piezoelectric ceramic plate to the third piezoelectric ceramic plate (110, 120, 130) is laminated so that the polarization direction is reverse to each other.

In the first piezoelectric ceramic plate 110, a first a electrode 111 is formed on an upper surface thereof, a first b electrode 113 is formed on a lower surface thereof, and a first b electrode 113 is formed in a direction from the first b electrode 113 to the first a electrode 111. It is preferred to be polarized. In this case, the first electrode 111 is defined as a first external electrode.

The second piezoelectric ceramic plate 120 has a second b electrode 123 formed on an upper surface thereof, and is bonded to the first b electrode 113 of the first piezoelectric ceramic plate 110, and a second a electrode 121 formed on a lower surface thereof. It is preferably formed to be polarized in the direction of the 2a electrode 121 from the second b electrode 123. In this case, the first b electrode 113 and the second b electrode 123 may be integrally formed, which is defined as a second internal electrode.

In the third piezoelectric ceramic plate 130, a third a electrode 131 is formed on an upper surface of the third piezoelectric ceramic plate 130 to be bonded to the second a electrode 121 of the second piezoelectric ceramic plate 120, and a third b electrode 133 is formed on a lower surface of the third piezoelectric ceramic plate 130. It is preferably formed to be polarized from the third b electrode 133 toward the third a electrode 131. In this case, the 2a electrode 121 and the 3a electrode 131 may be integrally formed, which is defined as a first internal electrode, and the 3b electrode 133 is defined as a second external electrode.

In this case, the first, second and third electrode electrodes 111, 121, and 131 of the first, second, and third piezoelectric ceramic plates 110, 120, and 130 are electrically connected to each other, and the first, second, and third piezoelectric ceramic plates, 110, 120, and 130 The first, second and third electrode (113, 123, 133) of the () is electrically connected to each other. In this case, the first to third electrodes 111, 121 and 131 and the first to third electrodes 113, 123 and 133 are insulated from each other.

Thus, a first external electrode is formed on an upper surface of the first piezoelectric ceramic plate 110, a second external electrode is formed on a lower surface of the third piezoelectric ceramic plate 130, and the first piezoelectric ceramic plate 110 is formed. ) And a second internal electrode electrically connected to the second external electrode are formed between the second piezoelectric ceramic plate 120 and the second piezoelectric ceramic plate 120 and the third ceramic plate 130. A first internal electrode electrically connected to the first external electrode is formed.

In other words, the first to third electrodes 111, 121, and 131 of the first to third piezoelectric ceramic plates 110, 120, and 130 are formed on the first piezoelectric ceramic plate 110 to be electrically connected to each other. The 2a electrode 121 formed on the 1a electrode 111 and the second piezoelectric ceramic plate 120 is electrically formed by the first via plug 160 passing through the first and second piezoelectric ceramic plates 110 and 120. The second a electrode 121 formed on the second piezoelectric ceramic plate 120 and the third a electrode 131 formed on the third piezoelectric ceramic plate 130 are bonded to each other and electrically connected to each other.

The first b electrodes to the third b electrodes 113, 123, and 133 of the first to third piezoelectric ceramic plates 110, 120, and 130 may be electrically connected to each other, and may be formed on the first piezoelectric ceramic plate 110. The second b electrode 123 formed on the 113 and the second piezoelectric ceramic plate 120 are bonded to each other and electrically connected to each other, and the second b electrode 123 formed on the second piezoelectric ceramic plate 120 and the second b electrode 123. The third b electrode 133 formed on the third piezoelectric ceramic plate 130 is electrically connected by a second via plug 170 passing through the second and third piezoelectric ceramic plates 120 and 130.

The vibration-inducing ceramic plate 140 is a ceramic that does not have a piezoelectric characteristic because it does not polarize in the thickness direction, and causes and amplifies the vibration occurring in the third piezoelectric ceramic plate 130 or directly serves as a vibration plate.

A pair of fourth b electrodes 143 electrically connected to the third b electrodes 133 is formed on both surfaces of the vibration induced ceramic plate 140. In this case, the fourth b electrode 143 and the third b electrode 133 formed on the upper surface of the vibration-inducing ceramic plate 140 may be integrally formed to become a second external electrode. In addition, the fourth b electrode 143 formed on the bottom surface of the vibration-inducing ceramic plate 140 is defined as a third external electrode.

At this time, the fourth b electrode 143 formed on the bottom surface of the vibration-inducing ceramic plate 140 extends the second via plug 170 and is electrically connected to the second external electrode.

In other words, the pair of 4b electrodes 143 extends the second via plug 170 to the vibration-inducing ceramic plate 140 so as to be electrically connected to the third negative electrode 133. A pair of agents formed on both surfaces of the second b electrode 123 formed on the plate 120, the third b electrode 133 formed on the third piezoelectric ceramic plate 130, and the vibration induced ceramic plate 140. The 4b electrode 143 is electrically connected by the second via plug 170.

Of course, the via plug connection method is adopted to electrically connect the first to third electrodes 111, 121 and 131 and the first and fourth electrodes 113, 123, 133 and 143 to each other, but is not limited thereto. Various methods of connection for electrically connecting the 3a electrodes 111, 121, 131 and the 1b electrodes to the 4b electrodes 113, 123, 133, 143 may be adopted and used.

In the piezoelectric element configured as described above, the first external electrode and the third external electrode are connected to the (+) pole and the (-) pole of the power supply means 10 to receive power.

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

As illustrated in FIG. 2, the piezoelectric element 200 according to the second exemplary embodiment includes first to third piezoelectric ceramic plates 210, 220, and 230 that are polarized and stacked in a thickness direction. The piezoelectric ceramic plate 230 has a thickness greater than that of the first and second piezoelectric ceramic plates 210 and 220.

The configuration and shape of the first piezoelectric ceramic plate to the third piezoelectric ceramic plate 210, 220, 230 correspond to the configurations of the first piezoelectric ceramic plate to the third piezoelectric ceramic plate 110, 120, 130 shown in the above-described first embodiment. However, in the present embodiment, it is preferable that the thickness of the third piezoelectric ceramic plate 230 is formed to be thicker than the thicknesses of the first and second piezoelectric ceramic plates 210 and 220.

As the thickness of the third piezoelectric ceramic plate 230 is formed to be thicker than the thickness of the first and second piezoelectric ceramic plates 210 and 220, the polarization state of the third piezoelectric ceramic plate 230 is increased. The polarization vibration is caused by the polarization difference by maintaining the state in which the ceramic plates 210 and 220 are less than the polarization state.

Unexplained reference numerals 260 and 270 are via plugs.

The configuration of a piezoelectric speaker using the piezoelectric element configured as described above will be described with reference to the drawings.

3 to 5 are schematic cross-sectional views showing piezoelectric speakers of various embodiments according to the present invention.

3 to 5, the piezoelectric speaker according to the embodiment of the present invention includes a diaphragm 300; First and second piezoelectric elements 100a and 100b, 200a and 200b, 100 and 200, which are bonded to both surfaces of the diaphragm 300, include the first and second piezoelectric elements 100a and 100b, 200a and 200b. , 100 and 200 are formed different from each other.

The diaphragm 300 is a means for acoustically converting a mechanical signal generated by an electrical signal applied to the first and second piezoelectric elements 100a and 100b, 200a and 200b, 100 and 200, and includes a metal diaphragm and a polymer. Various diaphragms such as a diaphragm diaphragm and a pulp diaphragm may be used. In the present embodiment, it is preferable to use a polymer-based diaphragm and a pulp-based diaphragm having a sound pressure drop phenomenon at the lowest resonant frequency or frequency band, compared to the metal diaphragm.

The first and second piezoelectric elements 100a and 100b, 200a and 200b, 100 and 200 use the piezoelectric elements 100 and 200 manufactured by the first and second embodiments described above. However, as the sizes of the first piezoelectric elements 100a, 200b and 100 and the second piezoelectric elements 100b, 200b and 200 are different from each other, the first and second piezoelectric elements 100a and 100b, 200a and 200b, By using the difference in the resonance frequency generated in the 100 and 200) to compensate for the portion of the sound pressure generated between the resonance and the resonance is reduced to achieve a uniform sound pressure.

The sizes of the first and second piezoelectric elements 100a and 100b, 200a and 200b, 100 and 200 may be formed in any size as long as they are different from each other, and have a resonance frequency applied to a product to which the piezoelectric speaker is applied. It is preferable that the size of the piezoelectric element is changed in various ways.

Referring to FIG. 3, the piezoelectric speaker 1000 according to the first embodiment of the present invention bonds the piezoelectric elements 100 manufactured by the first embodiment to both surfaces of the diaphragm 300.

The configurations of the first and second piezoelectric elements 100a and 100b are omitted because they are overlapped with the description of the piezoelectric elements according to the first embodiment.

However, it is preferable that the first and second piezoelectric elements 100a and 100b respectively bond the vibration-inducing ceramic plates 140a and 140b to the vibration plate 300. Thus, the vibration of the vibration-inducing ceramic plates 140a and 140b is directly transmitted to the vibration plate 300 so that the vibration efficiency of the vibration plate 300 is improved.

In addition, the sizes of the first and second piezoelectric elements 140a and 140b bonded to the diaphragm 300 are different from each other so that the resonance frequencies generated from the first and second piezoelectric elements 140a and 140b are different from each other. Do it.

Referring to FIG. 4, the piezoelectric speaker 2000 according to the second embodiment of the present invention bonds piezoelectric elements 200 manufactured by the second embodiment to both surfaces of the diaphragm 300.

The configurations of the first and second piezoelectric elements 200a and 200b will be omitted since they are overlapped with the description of the piezoelectric elements according to the second embodiment.

However, it is preferable that the first and second piezoelectric elements 200a and 200b respectively bond the third piezoelectric ceramic plates 230a and 230b to the diaphragm 300. Thus, vibrations of the third piezoelectric ceramic plates 230a and 230b are directly transmitted to the diaphragm 300 so that the vibration efficiency of the diaphragm 300 is improved.

Referring to FIG. 5, the piezoelectric speaker 3000 according to the third exemplary embodiment of the present invention bonds the piezoelectric element 100 manufactured by the first exemplary embodiment to one surface of the diaphragm 300, and the other surface of the diaphragm 300. The piezoelectric element 200 manufactured by the 2nd Example was bonded together.

The configuration of the first and second piezoelectric elements is omitted because it is a description overlapping with the description of the piezoelectric elements according to the first and second embodiments described above.

However, the first piezoelectric element 100 bonds the vibration-inducing ceramic plate 140 to the vibration plate 300, and the second piezoelectric element 200 connects the third piezoelectric ceramic plate 230 to the vibration plate 300. It is preferable to join to. Thus, the vibration of the third piezoelectric ceramic plate 230 is directly transmitted to the diaphragm 300 so that the vibration efficiency of the diaphragm 300 is improved.

Next, an experiment was carried out to find the resonant frequencies for each frequency band of the piezoelectric speaker according to the present invention.

6 is a graph showing resonant frequencies for each frequency band of a piezoelectric speaker according to an exemplary embodiment of the present invention. FIG. 6 is a piezoelectric speaker 1000 bonded to both sides of a diaphragm by varying the size of the piezoelectric element according to the first embodiment. ) Was used for the experiment.

As can be seen in FIG. 6, the resonance frequency implemented in the first piezoelectric element 100a and the resonance frequency implemented in the second piezoelectric element 100b do not coincide with each other. Accordingly, in the piezoelectric speaker having the first piezoelectric element 100a and the second piezoelectric element 100b bonded to both surfaces, sound pressure generated between resonances of the first and second piezoelectric elements 100a and 100b, respectively, is inhibited. It is possible to express the flat acoustic energy by supplementing them.

Although described above with reference to the drawings and embodiments, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit of the invention described in the claims below. I can understand.

100,200: piezoelectric element
110, 120, 130, 210, 220, 230: first to third piezoelectric ceramic plates
140: vibration induced ceramic plate
111, 121, 131, 211, 221, 231: (+) electrode
113, 123, 133, 143, 213, 223, 233: (-) electrode
160, 170, 260, 270: Via Plug
1000,2000,3000: piezoelectric speaker

Claims (11)

A piezoelectric element vibrates when a signal voltage is applied to an electrode.
At least three or more layers of piezoelectric ceramic plates are polarized and laminated in the thickness direction,
Each of the piezoelectric ceramic plates is a piezoelectric element laminated so that the polarization direction is reverse to each other.
The method according to claim 1,
The piezoelectric ceramic plates are sequentially laminated in a downward direction on the first to third piezoelectric ceramic plates,
A first external electrode is formed on an upper surface of the first piezoelectric ceramic plate, a second external electrode is formed on a lower surface of the third piezoelectric ceramic plate, and the first piezoelectric ceramic plate is formed between the first piezoelectric ceramic plate and the second piezoelectric ceramic plate. 2. A piezoelectric element having a second internal electrode electrically connected to an external electrode, wherein a first internal electrode electrically connected to the first external electrode is formed between the second piezoelectric ceramic plate and the third ceramic plate.
The method according to claim 2,
On the lower surface of the third piezoelectric ceramic plate, an unpolarized vibration-inducing ceramic plate is laminated while being electrically connected by the second external electrode,
And a third external electrode electrically connected to the second external electrode on a bottom surface of the vibration-inducing ceramic plate.
The method according to claim 3,
The first external electrode and the first internal electrode are electrically connected by first via plugs penetrating the first and second piezoelectric ceramic plates.
And the second and third external electrodes and the second internal electrode are electrically connected by a second via plug passing through the second and third piezoelectric ceramic plates and the vibration-inducing ceramic plate.
The method according to claim 2,
The piezoelectric element of claim 3, wherein the thickness of the third piezoelectric ceramic plate is greater than that of the first and second piezoelectric ceramic plates.
The method according to claim 5,
The first external electrode and the first internal electrode are electrically connected by first via plugs penetrating the first and second piezoelectric ceramic plates.
And the second and second internal electrodes are electrically connected to each other by a second via plug passing through the second and third piezoelectric ceramic plates and the vibration-inducing ceramic plate.
A diaphragm;
First and second piezoelectric elements bonded to both surfaces of the diaphragm,
The first and second piezoelectric elements are piezoelectric speakers different in size from each other.
The method according to claim 7,
The first and second piezoelectric elements each include at least three or more layers of piezoelectric ceramic plates that are polarized and stacked in a thickness direction, and each of the piezoelectric ceramic plates is laminated so that the polarization directions are reverse to each other.
The method of claim 8, wherein the first and second piezoelectric elements
The first to third piezoelectric ceramic plates are sequentially laminated in the downward direction, respectively,
Wherein each of the vibration-inducing ceramic plates that are not polarized is selectively bonded to the third piezoelectric ceramic plate, or the thickness of the third piezoelectric ceramic plate is thicker than the thickness of the first and second piezoelectric ceramic plates.
The method of claim 9, wherein the first and second piezoelectric elements
And a third piezoelectric ceramic plate formed thicker than the vibration-inducing ceramic plate or the first and second piezoelectric ceramic plates is bonded to the vibration plate.
The method according to any one of claims 7 to 10,
And the diaphragm is a polymer material or pulp.

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