KR20190018251A - Piezoelectric device, piezoelectric actuator including the device, and piezoelectric module including the actuator - Google Patents

Abstract

According to an embodiment, a piezoelectric element comprises a piezoelectric part having a plate shape having a height, a lateral width greater than the height, and a vertical width greater than the lateral width, a plurality of internal electrodes disposed in parallel inside the piezoelectric part and spaced apart in the vertical width direction, an external electrode disposed on a side surface of the piezoelectric part defined by the height and the vertical width, and a protective part covering the piezoelectric part and the external electrode; and a polarization direction and a longitudinal direction of the piezoelectric part coincide with each other, and a sound signal is transmitted through one surface of the piezoelectric part defined by the vertical width and the lateral width.

Description

[0001] The present invention relates to a piezoelectric element, a piezoelectric actuator including the piezoelectric actuator, and a piezoelectric module including the piezoelectric actuator,

Embodiments relate to a piezoelectric element, a piezoelectric actuator including the element, and a piezoelectric module including the actuator.

Generally, a piezoelectric element is a device having a characteristic capable of changing electric energy and mechanical energy with each other.

A piezoelectric speaker is a representative product of acoustic components that generate acoustic waves of a desired frequency band by acoustically converting the mechanical movement of such piezoelectric elements by a diaphragm. At this time, the piezoelectric element generates a voltage by the force applied to the piezoelectric ceramics, and the amount of voltage generated according to the strength of the piezoelectric element changes.

In general, a piezoelectric speaker having a good characteristic means that a high output is realized, a sound pressure is high in frequency, a flat shape is formed, and a wide sound range is obtained. However, in the case of the conventional piezoelectric element, polarization is caused in a direction intersecting with the main displacement direction, so that the vibration power is weak.

An embodiment provides a piezoelectric element having a high vibration force and a low resonance frequency, a piezoelectric actuator including the element, and a piezoelectric module including the actuator.

The piezoelectric device according to an embodiment includes a piezoelectric unit having a height, a width larger than the height, and a width longer than the width, the piezoelectric unit having a plate shape; A plurality of internal electrodes arranged in parallel within the piezoelectric portion and spaced apart in the longitudinal direction; An external electrode disposed on a side surface of the piezoelectric portion defined by the height and the vertical width; And a protective portion covering the piezoelectric portion and the external electrode. The polarization direction and the longitudinal direction of the piezoelectric portion coincide with each other, and the acoustic signal can be transmitted through one side of the piezoelectric portion defined by the lateral width and the vertical width.

For example, the external electrode may include a first external electrode disposed on one side of the side surface of the piezoelectric portion; And a second external electrode disposed on the other side of the side surface of the piezoelectric portion opposite to the one side surface.

For example, the plurality of internal electrodes may include a first internal electrode and a second internal electrode alternately arranged alternately and spaced apart from each other in the longitudinal direction of the piezoelectric portion, and the first internal electrode and the second internal electrode, The first internal electrode is exposed to the one side surface of the piezoelectric portion and is electrically connected to the first external electrode, and the second internal electrode is electrically connected to the other side surface of the piezoelectric portion, And may be electrically connected to the second external electrode.

For example, the piezoelectric unit may include a plurality of unit blocks stacked in the polarization direction, each of the unit blocks including the plurality of internal electrodes and including a ceramic-based piezoelectric material; And a first adhesive layer for bonding adjacent unit blocks among the plurality of unit blocks.

For example, each of the plurality of unit blocks may include a dummy portion disposed between the first adhesive layer and the inner electrode closest to the first adhesive layer among the plurality of inner electrodes; And a polarized portion disposed between the first and second internal electrodes.

For example, the plurality of internal electrodes may include a first dummy electrode exposed on the other side of the piezoelectric portion, spaced apart from the first internal electrode, and arranged on the same line as the first internal electrode; And a second dummy electrode exposed on the one side surface of the piezoelectric portion, spaced apart from the second internal electrode, and arranged on the same line as the second internal electrode.

For example, the plurality of internal electrodes may further include third and fourth dummy electrodes disposed on the same and spaced apart from each other on the one side surface and the other side surface of the piezoelectric portion in the dummy portion .

For example, in the transverse direction, the length of each of the first, second, third, and fourth dummy electrodes may be smaller than the length of the internal electrode.

For example, in the longitudinal axis direction, the length of the first adhesive layer may be smaller than the length of the polarized portion, and in the longitudinal direction, the length of the dummy portion may be smaller than the length of the polarized portion.

For example, the length of the first adhesive layer in the longitudinal direction is 0 to 20 μm or less, the length of the dummy portion in the longitudinal direction is 10 μm to 50 μm, and the length of the polarized portion in the longitudinal direction is 20 μm Lt; / RTI >

A piezoelectric actuator according to another embodiment includes a first piezoelectric element; A display unit disposed on the first piezoelectric element; A second adhesive layer disposed between the first piezoelectric element and the display portion; And a cover member disposed on the display portion, wherein the first piezoelectric element has a height, a width greater than the height, and a width longer than the width, the piezoelectric element having a plate shape; A plurality of internal electrodes arranged in parallel within the piezoelectric portion and spaced longitudinally apart; An external electrode disposed on a side surface of the piezoelectric portion defined by the height and the vertical width; And a protective portion covering the piezoelectric portion and the external electrode, wherein the polarization direction and the longitudinal direction of the piezoelectric portion coincide with each other, and the first acoustic signal can be transmitted through one side of the piezoelectric portion defined by the lateral width and the vertical width have.

For example, the piezoelectric actuator may further include a second piezoelectric element for outputting an electrical signal generated in response to the second acoustic signal, and the longitudinal direction and the polarization direction of the second piezoelectric element may intersect with each other.

For example, the piezoelectric actuator may further include a back plate disposed between the second adhesive layer and the display unit to protect the display unit.

For example, the piezoelectric actuator includes a diaphragm disposed below the piezoelectric element; A fixing plate disposed under one end of both ends of the diaphragm; And a third adhesive layer for bonding the piezoelectric element to the diaphragm.

For example, the piezoelectric actuator may further include a mass portion disposed below the other end of both ends of the diaphragm.

According to another embodiment of the present invention, there is provided a piezoelectric module comprising: a piezoelectric actuator; And a drive control section for driving the piezoelectric actuator, wherein the piezoelectric actuator comprises: a piezoelectric element; A display unit disposed on the piezoelectric element; A second adhesive layer disposed between the piezoelectric element and the display unit; And a cover member disposed on the display unit, wherein the piezoelectric element has a plate shape, the plate having a height, a width greater than the height, and a width greater than the width; A plurality of internal electrodes arranged in parallel within the piezoelectric portion and spaced longitudinally apart; An external electrode disposed on a side surface of the piezoelectric portion defined by the height and the vertical width; And a protective portion covering the piezoelectric portion and the external electrode. The polarization direction and the longitudinal direction of the piezoelectric portion coincide with each other, and the acoustic signal can be transmitted through one side of the piezoelectric portion defined by the lateral width and the vertical width.

The piezoelectric element according to the embodiment, the piezoelectric actuator including the element, and the piezoelectric module including the actuator can maximize the vibration power with a large displacement amount, have a low resonance frequency, have a slim thickness, It is possible to prevent the external electrode from being broken or lifted and to completely insulate the internal electrode from the outside to reinforce the flexural strength of the piezoelectric portion embodied as a plurality of stacked unit blocks, And it is possible to reinforce the bonding force of the joint portion by disposing it so as to be enclosed in the protective portion, and has a high degree of design freedom.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. It is to be understood, however, that the technical features of the present invention are not limited to the specific drawings, and the features disclosed in the drawings may be combined with each other to constitute a new embodiment.
1 is an exploded perspective view of a piezoelectric element according to an embodiment.
Fig. 2 is a perspective view showing the appearance of the piezoelectric element shown in Fig. 1. Fig.
3 is an external perspective view of the piezoelectric portion and the internal electrode shown in FIG. 1 according to an embodiment of the present invention.
FIG. 4 is a plan view of the piezoelectric portion and the internal electrode shown in FIG. 3 according to an embodiment of the present invention.
5 is a plan view of another embodiment of the piezoelectric portion and the internal electrode shown in Fig.
6 is a plan view of another embodiment of the piezoelectric portion and the internal electrode shown in Fig.
Figs. 7 (a) to 7 (e) show a planar shape of each of the first to fourth dummy electrodes.
8A to 8C show process perspective views for explaining the manufacturing method of the piezoelectric portion.
9 is a perspective view of a piezoelectric element according to a comparative example.
10 is a cross-sectional view of a piezoelectric actuator according to an embodiment.
11 is a sectional view of a piezoelectric actuator according to another embodiment.
12 is a sectional view of a piezoelectric actuator according to another embodiment.
13 is a perspective view of a piezoelectric module according to an embodiment.
14 is a flowchart for explaining a driving method according to an embodiment of a piezoelectric element serving as a speaker.
15 is a flowchart for explaining a driving method according to an embodiment of a piezoelectric element serving as a receiver.
16 is a flowchart for explaining a distortion compensation method of the first sound signal according to the embodiment.
Fig. 17A schematically shows an external perspective view of a conventional cellular phone, and Fig. 17B shows an external perspective view of the cellular phone according to the embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate understanding of the present invention. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the invention are provided to more fully describe the present invention to those skilled in the art.

In the description of the embodiment according to the present invention, in the case of being described as being formed on the "upper" or "on or under" of each element, on or under includes both elements being directly contacted with each other or one or more other elements being indirectly formed between the two elements. Also, when expressed as "on" or "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

It is also to be understood that the terms "first" and "second," "upper / upper / upper," and "lower / lower / lower" But may be used to distinguish one entity or element from another entity or element, without necessarily requiring or implying an order.

Hereinafter, the piezoelectric device 1000 according to the embodiment, the piezoelectric actuators 2000A to 2000C including the device 1000, and the piezoelectric module 3000 including the actuator will be described using a Cartesian coordinate system. Is not limited to this. That is, according to the Cartesian coordinate system, the x-axis, the y-axis and the z-axis are orthogonal to each other, but the embodiment is not limited to this. That is, the x-axis, the y-axis, and the z-axis may cross each other instead of being orthogonal.

Fig. 1 is an exploded perspective view of a piezoelectric device 1000 according to an embodiment. Fig. 2 is an external perspective view of an embodiment of the piezoelectric device 1000 shown in Fig. 1. Fig. 3 is a cross- FIG. 4 is a plan view of the piezoelectric unit 100 and the internal electrode 200 shown in FIG. 3 according to an embodiment of the present invention. .

1 to 4, a piezoelectric device 1000 according to an embodiment includes a piezoelectric unit 100, an internal electrode 200, an external electrode 300, and a passivation layer 400 .

The piezoelectric element 1000 according to the embodiment can operate as a kind of speaker for converting an electrical signal into an acoustic signal. In addition, the piezoelectric element 1000 according to the embodiment may operate as a receiver (or a microphone) which converts a sound signal into an electrical signal.

The piezoelectric unit 100 may have a plate shape having a height (or a thickness) H, a width W and a longitudinal width L (or a length L), but the embodiment is not limited to the specific shape of the piezoelectric unit 100 It is not limited. Here, the lateral width W may be greater than the height H and the longitudinal width L may be greater than the lateral width W. [

The piezoelectric unit 100 may include N unit blocks and N-1 first adhesive layers 120. Here, N may be a positive integer of 2 or more.

Hereinafter, the case where N = 4 is shown in the first to third embodiments of the piezoelectric element 100 according to the embodiment, but the following description can also be applied to a case where N is less than or greater than four. 4 shows only a part of the first to fourth unit blocks B1 to B4 for convenience of explanation.

The first to fourth unit blocks B1 to B4 are stacked in the polarization direction. Here, the polarization direction coincides with the direction in which the internal electrodes 200 are arranged as the direction in which the polarization occurs. In addition, the polarization direction may be the longitudinal direction (e.g., the z-axis direction) of the piezoelectric unit 100.

Each of the first to fourth unit blocks B1 to B4 includes the internal electrode 200 and may include a ceramic piezoelectric material. The ceramic piezoelectric material may be a single crystal or a polycrystal. For example, single crystal ceramic-based piezoelectric material _{PZN-PT [Pb (Zn 2/3} Nb 1/3) O 3 -PbTiO 3] or _{PMN-PT [Pb (Mg 2/3} Nb 1/3) O 3 - PbTiO ₃ ]. Alternatively, the polycrystalline ceramic piezoelectric material may include a Pb-based or non-Pb-based basic composition. For example, the polycrystalline ceramic piezoelectric material having a Pb-based basic composition may include at least one of Pb (Zr, Ti) O ₃ or PZT (Pb Zirconate Titanate). Alternatively, the polycrystalline ceramic piezoelectric material having a non-Pb-based basic composition may include at least one of K _0.5 Na _0.5 NbO ₃ or KNN.

However, the material of the first to fourth unit blocks B1 to B4 is not limited to the ceramic-based piezoelectric material. That is, if stacking is possible, slicing can be performed, and internal electrodes IE1, IE2, DE1 to DE4 can be deposited or printed, the material of the first to fourth unit blocks B1 to B4 is a specific type of piezoelectric It is not limited to materials. For example, the internal electrodes IE1, IE2, and DE1 to DE4 may be formed by printing using a screen printing technique.

According to another embodiment, the material of the first to fourth unit blocks B1 to B4 may be a polymer-based piezoelectric material.

The first adhesive layer 120 is disposed between the plurality of unit blocks B1 to B4 and serves to bond the first to fourth adhesive layers B1 to B4 to each other. As described above, when N = 4, the piezoelectric unit 100 may include three first adhesive layers 120 (A11, A12, A13). The 1-1 adhesive layer A11 serves to adhere the first and second unit blocks B1 and B2 adjacent to each other and the 1-2 adhesive layer A12 serves to attach the second and third unit blocks A12, B2 and B3, and the first-third adhesive layer A13 serves to bond the third and fourth unit blocks B3 and B4 adjacent to each other.

In addition, the first adhesive layer 120 may include an epoxy-based adhesive material, but the embodiment is not limited to the specific constituent materials of the first adhesive layer 120.

Further, when lower the elastic modulus of the first adhesive layer 120 can lower the resonant frequency (f _o) of the piezoelectric element (1000). If the elastic modulus of the first adhesive layer 120 is less than 1 MPa, the inherent physical properties of the first adhesive layer 120 may be deteriorated and the adhesive force may be weak. Therefore, the modulus of elasticity of the first adhesive layer 120 may be 1 MPa or more. For example, the modulus of elasticity of the first adhesive layer 120 may be from 1 MPa to 25000 MPa, preferably from 100 MPa to 10000 MPa, more preferably from 200 MPa to 4000 MPa, but the embodiment is not limited thereto. In this way, the resonance frequency (f _o) of the case to adjust the elastic modulus of the first adhesive layer 120, the piezoelectric element 1000 is, for example, can be as low as 200 to 300 ㎐ ㎐ from 1 ㎑. This is a principle to lower the resonance frequency (f _o ) by raising the total mass increase rate relative to the total modulus of elasticity.

Meanwhile, the internal electrode 200 may be disposed inside the piezoelectric portion 100. For example, the internal electrode 200 may include a plurality of internal electrodes 200 disposed in parallel to the piezoelectric portion 100 and spaced apart in the longitudinal direction.

According to an embodiment, the plurality of inner electrodes 200 may include first and second inner electrodes IE1 and IE2.

In addition, the number of internal electrodes 200 included in each of the plurality of unit blocks B 1 to B 4 may be the same or different from each other. For example, in the case of FIGS. 3 and 4, the number of the internal electrodes 200 included in each of the first to fourth unit blocks B1 to B4 may be six and the same. For example, the second unit block B2 may include three first internal electrodes IE1 (IE211, IE212, IE213) and three second internal electrodes IE2 (IE221, IE222, IE223). 5 and 6, each of the first and third unit blocks B1 and B3 includes three first inner electrodes IE1 and three second inner blocks IE1, such as a second unit block B2, And an electrode (IE2).

In the unit blocks B1 to B4, the first and second internal electrodes IE1 and IE2 are spaced apart from each other in the longitudinal direction (e.g., the z-axis direction) of the piezoelectric unit 100, As shown in FIG. 4, the first internal electrodes IE1 (IE211, IE212, IE213) and the second internal electrodes IE2 (IE221, IE222, IE223) are arranged in the z-axis direction And are repeatedly arranged mutually alternately.

The lengths (x1, x2) in the transverse direction (e.g., the x-axis direction) of the first internal electrodes (IE1: IE211, IE212, IE213) and the second internal electrodes (IE2: IE221, IE222, IE223) May be smaller than the transverse width W of the piezoelectric portion 100 in the transverse direction (for example, the x-axis direction).

The side surface of the piezoelectric portion 100 is a surface defined by the height H and the longitudinal width L and may include one side surface S1 and the other side surface S2 opposite to each other.

The first internal electrode IE1 (IE211, IE212, IE213) may be exposed to one side S1 of the piezoelectric unit 100 and electrically connected to the first external electrode 310. [ The second internal electrode IE2 (IE221, IE222, IE223) may be exposed to the other side S2 of the piezoelectric unit 100 and electrically connected to the second external electrode 320. [

The first internal electrode IE1 may be a positive electrode and the second internal electrode IE2 may be a negative electrode. Alternatively, the first internal electrode IE1 may be a negative (-) electrode and the second internal electrode IE2 may be a positive (+) electrode.

The external electrode 300 may be disposed on the sides S1 and S2 of the piezoelectric unit 100 and may include first and second external electrodes 310 and 320. [

The first external electrode 310 may be disposed on one side S1 of the side surface of the piezoelectric unit 100 and may be connected to the first internal electrode IE1. Also, the first external electrode 310 may be electrically connected to the second dummy electrode DE2 and the third dummy electrode DE3, which will be described later.

The second external electrode 320 may be disposed on the other side S2 of the side surface of the piezoelectric unit 100 and connected to the second internal electrode IE2. Also, the second external electrode 320 may be electrically connected to the first dummy electrode DE1 and the fourth dummy electrode DE4, which will be described later.

The first internal electrodes IE1 included in each of the plurality of unit blocks B1 to B4 are electrically connected in common to one first external electrode 310 and included in each of the plurality of unit blocks B1 to B4 The second internal electrode IE2 may be electrically connected to one second external electrode 320 in common.

In addition, each of the first to fourth unit blocks B1 to B4 may include a dummy area (DA) and a polarization area (PA).

The dummy portion DA can be defined as an area between the first adhesive layer 120 and the inner electrode closest to the first adhesive layer 120 among the inner electrodes 200 in each unit block B1 to B4. For example, assuming that six internal electrodes (IE211 to IE213, IE221 to IE223) are arranged in the second unit block B2 as shown in Fig. 4, six internal electrodes (IE211 to IE213, IE221 The region between the internal electrode IE223 and the first adhesive layer A12 may correspond to the dummy portion DA since the internal electrode IE223 is disposed closest to the first adhesive layer A12.

Further, the polarized portion PA can be defined as an area between the first and second internal electrodes IE1 and IE2. For example, referring to FIG. 4, a region between the first internal electrode IE 213 and the second internal electrode IE 223 may correspond to the polarization unit PA.

Further, polarization does not occur in each of the first adhesive layers 120 (A11 to A13) and the dummy portion (DA), and polarization occurs only in the polarized portion PA. Therefore, in order to reduce the portion in which the polarization does not occur in the entire longitudinal width L in the longitudinal axis direction (for example, the z axis direction) of the piezoelectric portion 100, It is preferable that the first length z1 of the adhesive layer 120 (A11 to A13) and the second length z2 of the dummy portion DA be shorter.

A pile section (DA) is because it can lower the piezoelectric element 1000 increases the mechanical stress and weight increase modulus compared after polarization resonance frequency (f _o) of the pile unit (DA) is the is present may be preferred. That is, the second length z2 may be greater than zero.

The first length z1 of the first adhesive layer 120 (A11 to A13) may be smaller than the third length z3 of the polarized portion PA in the longitudinal direction (e.g., the z-axis direction). This is because when the first length z1 of the first adhesive layer 120 (A11 to A13) is large, the weight of the piezoelectric element 1000 increases and the vibration force can be attenuated. Further, the second length z2 of the dummy portion DA may be smaller than the third length z3 of the polarized portion PA in the longitudinal direction (e.g., z-axis direction).

For example, the first length z1 of the first adhesive layer 120 (A11 to A13) in the longitudinal direction (e.g., z-axis direction) may be 0 to 20 占 퐉, preferably 2 占 퐉 to 10 占 퐉 . For example, the second length z2 of the dummy portion DA in the longitudinal direction (e.g., the z-axis direction) is greater than 0 and less than 50 占 퐉, preferably 10 占 퐉 to 50 占 퐉, more preferably 30 Mu m or 40 mu m. For example, the third length z3 of the polarized portion PA in the longitudinal direction (e.g., the z-axis direction) may be 20 [mu] m to 100 [mu] m. However, the embodiment is not limited to the specific values of the first to third lengths z1, z2, z3.

FIG. 5 is a plan view of another embodiment of the piezoelectric unit 100 and the internal electrode 200 shown in FIG.

According to another embodiment, unlike the internal electrode 200 shown in FIG. 4, the internal electrode 200 shown in FIG. 5 further includes first and second dummy electrodes DE1 and DE2. Except for this, the internal electrode 200 shown in FIG. 5 is the same as the internal electrode 200 shown in FIG. 4, so that the same reference numerals are used for the same parts, and a duplicate description will be omitted.

Like the second unit block B2 shown in FIG. 4, the first unit block B1 shown in FIG. 5 also includes three first internal electrodes IE1 (IE111, IE112, IE113) and 3 Second internal electrodes (IE2: IE121, IE122, IE123).

The first dummy electrode DE1 may be exposed on the other side S2 of the piezoelectric portion 100 and may be spaced apart from the first internal electrode IE1 and disposed on the same line as the first internal electrode IE1. For example, it can be seen that the first dummy electrode DE1 disposed on the leftmost side of the piezoelectric unit 100 is arranged on the same line as the first internal electrode IE111 in the x-axis direction.

The second dummy electrode DE2 may be exposed on one side S1 of the piezoelectric unit 100 and spaced apart from the second internal electrode IE2 and may be arranged on the same line as the second internal electrode IE2 have. For example, it can be seen that the second dummy electrode DE2 disposed on the leftmost side of the piezoelectric unit 100 is arranged on the same line in the x-axis direction as the second internal electrode IE121.

When the first inner electrode IE1 is electrically connected to the first outer electrode 310 and the first dummy electrode DE1 is electrically connected to the second outer electrode 320, The first dummy electrode DE1 and the first internal electrode IE1 are electrically separated from each other. When the second internal electrode IE1 is electrically connected to the second external electrode 320 and the second dummy electrode DE2 is electrically connected to the first external electrode 310, , The second dummy electrode DE2 and the second internal electrode IE2 are electrically separated from each other.

For example, when each of the lengths (x1, x2) in the transverse direction (for example, the x-axis direction) of each of the first internal electrode IE1 and the second internal electrode IE2 is 200 μm to 500 μm, The distance Δx1 between the first dummy electrode DE1 and the first internal electrode IE1 and the distance Δx2 between the second dummy electrode DE2 and the second internal electrode IE2 are 100 Mu] m to 300 [mu] m, although the embodiment is not limited thereto.

6 is a plan view of another embodiment of the piezoelectric unit 100 and the internal electrode 200 shown in FIG.

According to another embodiment, unlike the internal electrode 200 shown in FIG. 5, the internal electrode 200 shown in FIG. 6 further includes third and fourth dummy electrodes DE3 and DE4. Except for this, the internal electrode 200 shown in FIG. 6 is the same as the internal electrode 200 shown in FIG. 5, so that the same parts are denoted by the same reference numerals and the duplicated description will be omitted.

As described above, like the first and second unit blocks B1 and B2 shown in FIGS. 4 and 5, the third unit block B3 shown in FIG. 6 also includes three first internal electrodes IE1, IE311, IE312, IE313) and three second internal electrodes (IE2: IE321, IE322, IE323).

The third and fourth dummy electrodes DE3 and DE4 may all be disposed in the dummy portion DA. The third dummy electrodes DE3 and DE32 are exposed on one side S1 of the piezoelectric unit 100 and the fourth dummy electrodes DE4 and DE42 are exposed on the other side S2 of the piezoelectric unit 100. [ Lt; / RTI > The third and fourth dummy electrodes DE3 and DE4 may be arranged on the same line spaced apart from each other.

The third and fourth dummy electrodes DE3 and DE4 may be disposed in each of the dummy portions DA of the first to fourth unit blocks B1 to B4 as shown in FIG. The third and fourth dummy electrodes DE31 and DE41 are arranged in the dummy part DA of the second unit block B2 and the third and fourth dummy electrodes DE31 and DE41 are arranged in the dummy part DA of the third unit block B3. 4 dummy electrodes DE32 and DE42 may be disposed, but the embodiments are not limited thereto.

6, the third and fourth dummy electrodes DE3 and DE4 may be formed in any one of the dummy portions DA of the first to fourth unit blocks B1 to B4, The dummy part DA of the first embodiment.

When the third dummy electrode DE3 (DE31, DE32) is electrically connected to the first external electrode 310 and the fourth dummy electrode DE4 (DE41, DE42) is electrically connected to the second external electrode 320, The third dummy electrode DE3 and the fourth dummy electrode DE4 are electrically isolated from each other in order to prevent an electrical short between the first external electrode 310 and the second external electrode 320. [ For example, the distance DELTA x3 between the third dummy electrode DE3 and the fourth dummy electrode DE4 may be 100 mu m to 300 mu m, but the embodiment is not limited to this.

The thickness of each of the internal electrodes, i.e., the first internal electrode IE1, the second internal electrode IE2, and the first to fourth dummy electrodes DE1 to DE4 in the longitudinal direction (e.g., the z-axis direction) May be from 1 [mu] m to 2 [mu] m, although the embodiment is not limited thereto.

Although not shown, according to another embodiment, the internal electrode 200 does not include the first and second dummy electrodes DE1 and DE2, but includes only the third and fourth dummy electrodes DE3 and DE4 You may. In this case, the first and second dummy electrodes DE1 and DE2 shown in Fig. 6 may be omitted.

6, in which the third and fourth dummy electrodes DE3 and DE4 are disposed in the dummy portion DA of each unit block B1 to B4, although not shown, according to another embodiment, And fourth dummy electrodes DE3 and DE4 may be disposed in the first adhesive layer 120 (A11, A12, A13) between the unit block and the unit block.

6, in which the third and fourth dummy electrodes DE3 and DE4 are disposed in the dummy portion DA of each unit block B1 to B4, although not shown, according to another embodiment, And fourth dummy electrodes DE3 and DE4 may be disposed between the dummy portion DA of each unit block B1 to B4 and the first adhesive layer 120 (A11, A12, and A13). In this case, a region in which the third and fourth dummy electrodes DE3 and DE4 are disposed between the dummy portion DA and the first adhesive layer 120 in each of the unit blocks B1 to B4 can be additionally secured.

6, the lengths (x5, x6) of the third and fourth dummy electrodes DE3, DE4 are smaller than the lengths of the internal electrodes x1, x2, respectively, in the abscissa direction (for example, May be greater than the length (x3, x4) of each of the first and second dummy electrodes DE1, DE2.

The inner electrode 200 and the outer electrode 300 may be implemented as a conductive material, and embodiments are not limited to specific materials of the inner electrode 200 and the outer electrode 300, respectively.

As described above, the characteristics related to the internal electrodes IE1, IE2, and DE1 to DE4 included in the unit blocks B1 to B4, that is, the number of the internal electrodes IE1, IE2, DE1 to DE4, The lengths x1 and x2 of the second internal electrodes IE1 and IE2 and the lengths x3 and x4 of the first and second dummy electrodes DE1 and DE2 and the width in the vertical direction are all described as being the same The embodiment is not limited to this. That is, the characteristics related to the internal electrodes IE1, IE2, and DE1 to DE4 may be different for each unit block.

4, the width in the transverse direction (for example, the x-axis direction) of the empty spaces ES1 and ES2 in which no electrode is present between the first internal electrode IE1 and the other side S2 is 1 Mu m to 2 mu m. At this time, since the plurality of unit blocks B1 to B4 are stacked and arranged in the piezoelectric unit 100, the empty spaces ES1 and ES2 are accumulated so that the plurality of unit blocks B1 to B4 are flared or bent The reliability of the piezoelectric element 1000 may be deteriorated.

Therefore, as shown in FIGS. 5 and 6, the first and second dummy electrodes DE1 and DE2 are disposed in the empty spaces ES1 and ES2 in an alternating manner, or the third and fourth dummy electrodes ES1 and ES2, When the electrodes DE3 and DE4 are sequentially arranged in the longitudinal direction (for example, the z-axis direction), expansion of the plurality of unit blocks B1 to B4 due to accumulation of the empty spaces ES1 and ES2, The flexure phenomenon of the piezoelectric element 100 is prevented, and the reliability of the piezoelectric element 1000 can be improved.

Further, in order to further prevent a warping phenomenon of the piezoelectric portion 100, a groove portion may be provided between the plurality of unit blocks B1 to B4. For example, the grooves may be disposed in the first adhesive layer 120, but embodiments are not limited thereto.

3, the first adhesive layer A13 may have the same shape as the other first adhesive layers A11 and A12, and the first adhesive layers A11 and A12 may have the same shape as the other first adhesive layers A13 It is possible.

The grooves may be disposed symmetrically with respect to one side S1 and the other side S2 of the piezoelectric unit 100. [ Although the groove HO is formed only on one side S1 in the case of FIG. 3, it may also be formed symmetrically on the other side S2.

7 (a) to 7 (e) show planar shapes according to the embodiments of the first to fourth dummy electrodes DE1 to DE4, respectively.

In addition, the first to fourth dummy electrodes DE1 to DE4 described above may have various planar shapes, and the embodiment is not limited to the specific planar shapes of the first to fourth dummy electrodes DE1 to DE4. For example, each of the first to fourth dummy electrodes DE1 to DE4 may have a mesh-like planar shape as shown in Fig. 7 (a), and may have a planar shape as shown in Fig. 7 (b) 7 (c), it may have a planar shape in the form of a hole, or may have a planar shape in the form of a horizontal line, as shown in Fig. 7 (d) Or may have a planar shape in the form of a vertical line as shown in Fig. 7 (e).

1 and 2, the protection unit 400 may be disposed so as to cover the piezoelectric unit 100 in which the internal electrode 200 is embedded and the external electrode 400. For this purpose, the protection unit 400 may include first and second protection units 410 and 420.

1, the first protection unit 410 includes a top surface defined by a width W and a longitudinal width L of the piezoelectric unit 100, a top surface defined by the width W and the longitudinal width L of the piezoelectric unit 100, The second protective portion 420 is disposed to cover the upper surface of each of the first and second external electrodes 310 and 320 and the lower surface of the upper surface of the piezoelectric portion 100, And may be arranged to cover the opposite lower surface of the upper surface.

According to another embodiment, at least one of the first or second protective portions 410 and 420 may be arranged to further cover all the sides of the first and second external electrodes 310 and 320, respectively. In this case, as illustrated in FIG. 2, the piezoelectric portion 100, the internal electrode 200 and the external electrode 300 disposed in the piezoelectric portion 100 may be in a completely sealed form by the protection portion 400 .

In addition, the protection unit 400 may be formed of a material having excellent electrical insulation and waterproofness. In addition, the protective portion 400 may be formed of a material having a high adhesive force and a low mechanical strain. For example, the protector 400 may include at least one of Urethane, Epoxy, Silicone, or Acryl, but the embodiment is not limited thereto.

Further, the protection unit 400 is 2 MPa to about a 300 MPa modulus of elasticity (modulus) and, 5MPa to 45 MPa in the adhesive strength and, from 30 to 70 hardness, and a thickness of 20 ㎛ to 70 ㎛ (t1) and 1x10 least ⁹ Ω of It can have an insulation rate.

By disposing the protection unit 400 described above, it is possible to prevent the outer electrode 300 of the piezoelectric element 1000 vibrating at a large amplitude from being broken or lifted, and by completely insulating the inner electrode 200 from the outside, The bending strength of the piezoelectric unit 100 implemented by the plurality of unit blocks B1 to B4 stacked can be reinforced.

13, when the external electrode 300 is connected to the driving control unit 2500 through the wirings 2610 and 2620, the external electrode 300 and the wirings 2610 and 2620 are bonded to each other By arranging the joint portion (for example, soldering portion) so as to surround the protective portion 400, the adhesion force of the joint portion can be reinforced.

Hereinafter, a method of manufacturing the piezoelectric portion 100 shown in FIG. 4 will be described with reference to FIGS. 8A to 8C. However, the piezoelectric portion 100 shown in Fig. 4 can be manufactured by a method different from Figs. 8A to 8C. It is needless to say that the piezoelectric unit 100 shown in Figs. 5 and 6 can also be manufactured by the method shown in Figs. 8A to 8C. In the following description, it is assumed that the number of unit blocks is four.

8A to 8C show a process perspective view for explaining the manufacturing method of the piezoelectric unit 100. Fig.

Referring to FIG. 8A, a piezoelectric structure 100A in which an internal electrode 200 is disposed is prepared.

As shown in FIG. 8A, the internal electrode 200 disposed in the piezoelectric structure 100A is the internal electrode 200 shown in FIG. 4, which does not include the first to fourth dummy electrodes DE1 to DE4. If the internal electrode 200 disposed in the piezoelectric structure 100A includes the first and second dummy electrodes DE1 and DE2 shown in FIG. 5, FIGS. 8A to 8C show the relationship between the voltage It may correspond to the manufacturing method of the front part 100.

Alternatively, when the internal electrode 200 disposed in the piezoelectric structure 100A shown in FIG. 8A includes the first through fourth dummy electrodes DE1 through DE4 shown in FIG. 6, FIGS. 8A through 8C are diagrams 6 may correspond to a manufacturing method of the piezoelectric unit 100 shown in FIGS.

8B, the piezoelectric structure 100A shown in FIG. 8A is vertically stacked in the z-axis direction. At this time, the adjacent piezoelectric structures 100A can be bonded by the first adhesive layer 120 (A11, A12, A13).

8B is sliced in the direction of arrow A1, the piezoelectric unit 100 shown in FIG. 8C can be completed.

For example, when the width X1 of the piezoelectric structure 100A shown in FIG. 8A in the transverse direction (for example, the x-axis direction) is 17 mm and the width X1 in the vertical direction The thickness Z1 in the thickness direction (for example, the z-axis direction) is 1.5 mm and the thickness Y1 in the thickness direction of the laminated resultant shown in Fig. 8B And the thickness Y2 in the thickness direction (e.g., the y-axis direction) of the sliced resultant shown in Fig. 8C (i.e., the height H shown in Fig. 3) ) Is 0.45 mm, 69 piezoelectric units 100 can be obtained.

Hereinafter, a piezoelectric device according to a comparative example and an example will be described with reference to the accompanying drawings.

9 shows a perspective view of the piezoelectric element 10 according to a comparative example.

The piezoelectric element 10 according to the comparative example shown in Fig. 9 may include the internal electrode 20 and the piezoelectric portion 30. Fig. Here, the internal electrode 20 and the piezoelectric unit 30 may play the same role as the internal electrode 200 and the piezoelectric unit 100 according to the above-described embodiment.

When the piezoelectric element 1000 according to the above embodiment performs a role of a speaker, an acoustic signal may be transmitted through one surface of the piezoelectric portion 100 defined by the width W and the width L. Alternatively, when the piezoelectric element 1000 according to the above-described embodiment performs a role of a receiver, an electrical signal corresponding to an external acoustic signal may be generated.

When the piezoelectric element 1000 according to the embodiment performs a role of a speaker and a pulse signal is applied to the internal electrode 200 through the external electrode 300, Can be generated. Here, the pulse signal is an electrical signal having amplitude and frequency, and may be a voltage signal or a current signal. For example, the pulse signal may have ac characteristics for imparting vibration to the piezoelectric material. At this time, the piezoelectric unit 100 vibrates in both the main displacement direction (e.g., the z-axis direction) and the sub displacement direction (e.g., the y-axis direction).

When the piezoelectric element 10 according to the comparative example shown in FIG. 9 performs a role of a speaker, when a pulse signal is applied to the internal electrode 20 through an external electrode (not shown) The sound signal can be generated. At this time, the piezoelectric portion 10 vibrates in both the main displacement direction (e.g., the z-axis direction) and the sub displacement direction (e.g., the y-axis direction).

9, the polarization direction (e.g., the y-axis direction) and the main displacement direction (for example, the z-axis direction) intersect with each other so that the displacement amount of the piezoelectric unit 30 not big.

On the other hand, in the case of the piezoelectric element 100 according to the embodiment, the polarization direction (for example, the z-axis direction) and the main displacement direction (for example, DD1 and DD2 are relatively larger than those of the piezoelectric element 10 according to the comparative example shown in Fig.

The strain (? ₃₁ ) of the piezoelectric element 10 according to the comparative example shown in FIG. 9 is expressed by the following equation (1), and the strain? ₃₃ of the piezoelectric element 1000 according to the embodiment is expressed by the following equation Can be expressed as Here, in the strain? _Jk , j and k represent the vibration direction and the alignment direction of the piezoelectric units 30 and 100, respectively. The values 1, 2, and 3 of j (or k) mean the x-axis, y-axis, and z-axis directions, respectively.

Here, d ₃₁ represents a first piezoelectric constant of the piezoelectric element 10, d ₃₃ represents a second piezoelectric constant of the piezoelectric element 1000, v is a pulse applied to the piezoelectric elements 10 and 1000, that is, , And t represents the thickness of the piezoelectric units 10 and 100. [

The strain? ₃₃ of the piezoelectric device 1000 according to the embodiment shown in the above-mentioned formula (2) is larger than the strain? ₃₁ of the piezoelectric device 10 according to the comparative example shown in the formula (1). This is because the thickness t decreases and the second piezoelectric constant d ₃₃ is larger than the first piezoelectric constant d ₃₁ . That is, when j and k match, the strain of the piezoelectric element can be increased.

In general, the vibration force of the piezoelectric units 30 and 100 is expressed by the following equation (3).

Here, F represents a vibration force, d represents a piezoelectric constant, and s represents a reciprocal of a modulus of elasticity as a stiffness.

Referring to Equation (3), s and t are smaller than those of the comparative example, and d is larger than that of the comparative example, so that the vibration force of the piezoelectric element 1000 according to the embodiment is smaller than that of the piezoelectric element 10 ).

The first bonding layers 120 (A11, A12, A13) according to the embodiment are formed in the polarization direction (e.g., the y-axis direction) in order to increase the amount of displacement of the piezoelectric element 10 shown in Fig. Can be vertically stacked. However, in this case, the thickness of the product using the piezoelectric element 10 in the y-axis direction can be increased.

On the other hand, in the case of the piezoelectric element 1000 according to the embodiment, even if the number of the plurality of unit blocks B 1 to B 4 is increased to further increase the amount of displacement of the piezoelectric element 1000, The thickness in the axial direction does not increase.

The change in length of the piezoelectric unit 100 according to the embodiment can be expressed by the following equation (4).

Here,? L represents a change in length in the longitudinal direction (for example, the z-axis direction) of the piezoelectric unit 100.

(3) and (4), the number N of stacked unit blocks increases, the applied voltage v increases, and the thickness t of the piezoelectric unit 100 (i.e., the height H) It can be seen that the vibration force F and the change in length DELTA L in the longitudinal direction (e.g., the z-axis direction) of the piezoelectric unit 100 can be further increased as the piezoelectric thin film thickness becomes thinner.

As a result, in the piezoelectric element 1000 according to the above-described embodiment, since the plurality of unit blocks B1 to B4 are stacked and disposed in the same direction as the polarization direction, not only the piezoelectric force of the piezoelectric unit 100 is high, first adhesive layer: by adjusting the elastic coefficient of the (120 A11, A12, A13) can lower the resonant frequency (f _o).

As in the embodiment, when the vibration force of the piezoelectric element 1000 is high, the piezoelectric element 1000 can provide a haptic function in addition to a speaker or a receiver, and can be applied to a proximity sensor.

Hereinafter, embodiments of the piezoelectric actuator including the piezoelectric element 1000 according to the above-described embodiment will be described with reference to the accompanying drawings.

10 shows a cross-sectional view of a piezoelectric actuator 2000A according to an embodiment.

The piezoelectric actuator 2000A shown in Fig. 10 may include a cover member 1100, a display portion 1200A, a second adhesive layer 1300, and a piezoelectric element 1400. Fig.

The display portion 1200A may be disposed under the cover member 1100. [

The cover member 1100 may be rigid or flexible. Preferably, the cover member 1100 may be flexible to be foldable or bending.

For example, the cover member 1100 may include plastic or glass. In detail, the cover member 1100 includes a reinforced or soft plastic such as polyimide (PI), polyethylene terephthalate (PET), propylene glycol (PPG), polycarbonate (PC) . ≪ / RTI >

Further, the cover member 1100 may include an optically isotropic film. For example, the cover member 1100 may include a cyclic olefin copolymer (COC), a cyclic olefin polymer (COP), a polycarbonate (PC), a light polymethyl methacrylate (PMMA), or the like.

The display portion 1200A may be an organic light emitting display (OLED) panel substrate. In this case, the display portion 1200A includes a self-luminous element that does not require a separate light source.

The second adhesive layer 1300 is disposed between the display portion 1200A and the piezoelectric element 1400 and serves to adhere the first and second adhesive layers 1300 and 1400 to each other. For example, the material of the second adhesive layer 1300 may be the same as or different from the material of the first adhesive layer 120 described above. For example, the second adhesive layer 1300 may be a transparent adhesive for optical, but the embodiment is not limited to the specific material of the second adhesive layer 1300. [

According to one embodiment, the piezoelectric element 1400 may include a first piezoelectric element 1410 and a second piezoelectric element 1420.

The first piezoelectric element 1410 may correspond to the piezoelectric element 1000 according to the above-described embodiment. That is, the first piezoelectric element 1410 receives a pulse from the drive control unit 2500 to be described later, and transmits an acoustic signal (hereinafter, referred to as a 'first acoustic signal') generated by vibrating the piezoelectric unit 100 It can act as a kind of speaker.

The second piezoelectric element 1420 may correspond to the piezoelectric element 10 according to the comparative example shown in Fig. That is, when the second piezoelectric element 1420 detects an acoustic signal (hereinafter referred to as a second acoustic signal) from the outside, the second piezoelectric element 1420 vibrates the piezoelectric unit 30 and generates a voltage corresponding to the vibration of the piezoelectric unit 30 And can output an electric signal to the drive control section 2500. The second piezoelectric element 1420 may serve as a receiver for receiving the second acoustic signal.

10, the piezoelectric element 1400 may be of a hybrid type including both the piezoelectric element 1410 according to the embodiment and the piezoelectric element 1420 according to the comparative example.

According to another embodiment, the piezoelectric element 1400 includes only the first piezoelectric element 1410, and the second piezoelectric element 1420 can be omitted. In this case, the first piezoelectric element 1410 may be a piezoelectric element 1000 according to the above-described embodiment, and may perform both a speaker and a receiver.

According to another embodiment, the piezoelectric element 1400 may include a plurality of first piezoelectric elements 1410. [

11 shows a cross-sectional view of a piezoelectric actuator 2000B according to another embodiment.

The piezoelectric actuator 2000B shown in Fig. 11 may include a cover member 1100, a display portion 1200B, a second adhesive layer 1300, a piezoelectric element 1400 and a back plate 1500 .

The cover member 1100, the second adhesive layer 1300 and the piezoelectric element 1400 shown in Fig. 11 correspond to the cover member 1100, the second adhesive layer 1300 and the piezoelectric element 1400 shown in Fig. 10, respectively The same reference numerals are used and redundant description is omitted.

The display portion 1200B may be disposed under the cover member 1100 and may include a thin film transistor (TFT).

The back plate 1500 is disposed between the second adhesive layer 1300 and the display portion 1200B to protect the display portion 1200B.

10 and 11, when the piezoelectric element 1400 vibrates, the display portions 1200A and 1200B arranged on the upper portion of the piezoelectric element 1400 also vibrate. At this time, the pixels of the display portions 1200A and 1200B may be broken by vibration. However, when the second adhesive layer 1300 is disposed between the display portions 1200A and 1200B and the piezoelectric element 1400 as shown in Figs. 10 and 11, the pixels of the display portions 1200A and 1200B are vibrated So that the risk of breakage can be solved.

The piezoelectric element 1400 vibrates in a direction (for example, the x-axis direction or the z-axis direction) perpendicular to the direction toward the display portions 1200A and 1200B, and repeats contraction and expansion. The lower surfaces of the display portions 1200A and 1200B facing the piezoelectric element 1400 receive the vibration force of the piezoelectric element 1400 and vibrate in the x-axis direction or the z-axis direction. The display unit 1200A and the display unit 1200B may generate vibrations in the y-axis direction while repeating contraction and expansion in the x-axis direction or the z-axis direction. At this time, 1200B may serve as diaphragms of a flat-plate speaker. Also, the waveforms generated in the display units 1200A and 1200B may be in the form of a bending wave. Specifically, a distributed mode speaker can be realized by arranging a single piezoelectric element 1400 asymmetrically up and down and / or horizontally with respect to the display area, or by using a plurality of piezoelectric elements 1400 or the like . The dispersion mode has low directivity and wide frequency characteristics, but the vibration power tends to be low.

Application of the piezoelectric element 1400 of the embodiment can increase the vibration power and lower the resonance frequency, thereby realizing a dispersion mode planar speaker having smooth output in the audible frequency band.

12 shows a cross-sectional view of a piezoelectric actuator 2000C according to another embodiment.

The piezoelectric actuator 2000C shown in Fig. 12 may include a diaphragm 1600, a third adhesive layer 1610, a fixing plate 1700, a mass portion 1800, and a piezoelectric element 1900. [

The piezoelectric element 1900 may correspond to the above-described piezoelectric element 1000 or the piezoelectric element 1400 shown in Fig. 10 or Fig.

The diaphragm 1600 may be disposed under the piezoelectric element 1900 and may be formed of a metal material such as aluminum (Al), a polymer material, a pulp, or the like.

The third adhesive layer 1610 is disposed between the piezoelectric element 1900 and the vibration plate 1600 and serves to adhere the piezoelectric elements 1900 and 1600 to each other.

The fixing plate 1700 is disposed below one end of the both ends of the diaphragm 1600 and serves to support the diaphragm 1600.

The mass portion 1800 may be disposed below the other end of both ends of the diaphragm 1600.

As shown in Fig. 12, when the piezoelectric actuator 2000C has a cantilever structure, the amount of displacement of the piezoelectric element 1900 can be further increased. Further, by arranging the mass portion 1800, the vibration force of the piezoelectric actuator 2000C can be further strengthened.

12 is 46 mm, the height H of the piezoelectric element 1900 is 2.4 mm, and the thickness t2 of the diaphragm 1600 is 0.2 Mm, the amount of displacement can be increased to about six times or more as compared with the piezoelectric element 10 shown in Fig.

In addition, the third adhesive layer 1610 may include an epoxy based adhesive material, but the embodiment is not limited to the specific constituent materials of the third adhesive layer 1610. Further, similarly to the first adhesive layer 120, when the elastic modulus of the third adhesive layer 1610 is lowered, the resonance frequency f _o of the first piezoelectric element 1900 can be lowered. For example, the modulus of elasticity of the third adhesive layer 1610 may be from 1 MPa to 25000 MPa, preferably from 100 MPa to 10000 MPa, more preferably from 50 MPa to 2000 MPa, but the embodiment is not limited thereto.

The material of the third adhesive layer 1610 and the first adhesive layer 120 may be equal to each other and the material of the third adhesive layer 1610 may have the same elastic modulus as the material of the first adhesive layer 120. [

In order to optimize the design of the piezoelectric actuator 2000C, the elastic coefficient determined by the material and shape of the fixed plate 1700 and the first piezoelectric element 1900 and the mass of the mass portion 1800 serving as a weight It is necessary to match the determined resonance frequency f _o with the vibration frequency of the piezoelectric actuator 2000C shown in Fig. 12 having a cantilever structure. That is, it is possible to design the piezoelectric actuator 2000C so that the following equation (5) is satisfied.

Here,? Is expressed by the following equation (6), and? Is expressed by the following equation (7).

Here, t _sub is as shown in Fig. And the thickness t _p denotes the thickness (i.e., the height H) of the piezoelectric element 1900. The thickness of the piezoelectric element 1900 is the same as that of the piezoelectric element 1900 shown in Fig.

Here, E _sub represents the elastic modulus of the portion excluding the piezoelectric element 1900 in FIG. 12, and E _p represents the elastic modulus of the piezoelectric element 1900.

The piezoelectric actuators 2000A to 2000C according to the embodiment are not limited to Figs. 10 to 12. Fig. That is, when the piezoelectric actuator has a TFT-LCD structure, an OLED structure, or a flexible OLED structure, the piezoelectric element can be disposed at the bottom in this structure.

Hereinafter, embodiments of the piezoelectric module including the piezoelectric actuator according to the above-described embodiments will be described with reference to the accompanying drawings.

13 is a perspective view of a piezoelectric module 3000 according to an embodiment.

The piezoelectric module 3000 shown in FIG. 13 may include a piezoelectric actuator, a drive control portion 2500, and wirings 2610 and 2620.

The piezoelectric actuators may correspond to the piezoelectric actuators 2000A to 2000C illustrated in Figs. 10 to 12. Fig. For convenience of explanation, in Fig. 13, components other than the piezoelectric element in the piezoelectric actuator are omitted.

13 may include the piezoelectric unit 100, the internal electrode 200, and the first and second external electrodes 310 and 320. In the piezoelectric unit 100, a plurality of unit blocks are bonded to each other by the first adhesive layers 120 (A11, A12, A13). The piezoelectric unit 100, the internal electrode 200, the first and second external electrodes 310 and 320, and the first adhesive layer 120 may be formed of the piezoelectric unit 100 shown in FIGS. 1 to 4, 200, the first and second external electrodes 310 and 320, and the first adhesive layer 120 (A11, A12, and A13), the same reference numerals are used, and redundant description will be omitted.

The drive control unit 2500 serves to drive the piezoelectric actuator. In particular, the driving control unit 2500 is connected to the piezoelectric elements through the wirings 2610 and 2620, and drives the piezoelectric elements. The wiring includes a first wiring 2610 electrically connecting the driving control unit 2500 and the first external electrode 310 and a second wiring electrically connecting the driving control unit 2500 and the second external electrode 320 2620).

The driving control unit 2500 may be connected to a substrate (not shown) such as an FPCB (Flexible Printed Circuit Board). The FPCB may provide a pulse to be applied to the external electrode 300 from the drive control unit 2500 to the drive control unit 2500 or may receive an electrical signal corresponding to the second sound signal provided from the drive control unit 2500 have.

An operation of the drive control unit 2500 for driving the piezoelectric element of the piezoelectric actuator will be described in detail as follows.

Fig. 14 is a flowchart for explaining a driving method 3100 according to an embodiment of a piezoelectric element serving as a speaker.

First, when the piezoelectric element serves as a speaker, the drive control section 2500 drives the piezoelectric element as follows.

The driving control unit 2500 applies a driving pulse having a suitable level to the internal electrode 200 through the external electrode 300 to vibrate the piezoelectric unit 100 (Step 3102). For example, when the pulse signal has a voltage form, a positive voltage is applied to the first internal electrode IE1 through the first external electrode 310 and a negative voltage is applied to the second external electrode 310. [ To the second internal electrode (IE2) through the second internal electrode (320). Or a negative voltage is applied to the first internal electrode IE1 through the first external electrode 310 and a positive voltage is applied to the second internal electrode IE2 through the second external electrode 320, IE2).

When the positive and negative voltages are respectively applied to the first and second internal electrodes IE1 and IE2, the piezoelectric unit 100 vibrates in the longitudinal direction (e.g., the z-axis direction) (Step 3104).

When the piezoelectric unit 100 vibrates and the vibration is transmitted to the display units 1200A and 1200B of the piezoelectric actuator through one side defined by the lateral width W and the longitudinal width L of the piezoelectric element 100, The display unit 1200A and the display unit 1200B oscillate in a vertical direction (e.g., a y-axis direction) intersecting with the vertical axis direction so that the first acoustic signal can be transmitted in the form of a bending wave step). Here, the excitation point means the point where the piezoelectric actuator is disposed.

15 is a flowchart for explaining a driving method 3200 according to an embodiment of a piezoelectric element serving as a receiver.

When the piezoelectric element shown in FIG. 13 serves as a receiver, the drive control section 2500 drives the piezoelectric element as follows.

When the second acoustic signal is transmitted from the outside to the piezoelectric device 100, the piezoelectric device 100 vibrates (Step 3202).

The vibration is converted into an electric signal form through the internal electrode 200 and the external electrode 300, and is transmitted to the drive control unit 2500 (Step 3204).

The drive control unit 2500 senses an acoustic signal using the electrical signal generated in accordance with the vibration (operation 3206).

14 and 15, the piezoelectric element may convert an electrical signal into a first acoustic signal or a second acoustic signal into an electrical signal.

On the other hand, while the first acoustic signal is being transmitted by the vibration of the piezoelectric unit 100, the transmitted first acoustic signal may be distorted by a change in external conditions. For example, when the user touches the display portions 2100A and 2100B while the first sound signal is being transmitted, distortion may be caused in the transmitted first sound signal.

Hereinafter, a distortion compensation method according to an embodiment for compensating distortion of a first sound signal in a piezoelectric module will be described with reference to the accompanying drawings.

16 is a flowchart for explaining a first sound signal distortion compensation method 3300 according to the embodiment.

The drive control unit 2500 checks whether there is a change in the displacement of the panel of the display unit (hereinafter referred to as 'display panel') that transmits the first sound signal (operation 3302).

If there is a displacement change of the display panel, a displacement change amount is obtained (operation 3304).

Thereafter, the level of the applied pulse, that is, the electric signal is adjusted so as to compensate for the displacement variation, and a pulse having the adjusted level is supplied to the internal electrodes IE1 and IE2 through the wirings 2610 and 2620 and the external electrode 300 (Operation 3306). Thus, the distortion of the first acoustic signal can be compensated.

The piezoelectric module according to the above-described embodiment can be applied to various devices having at least one of a speaker and a receiver. For example, the piezoelectric module according to an embodiment may be used in various applications such as mobile phones, multimedia Internet mobile phones, wireless devices, smart phones, Bluetooth devices, PDAs, portable computers, netbooks, a display device (including a traveling system and a speedometer), a cockpit control device, a display device, and the like, but the embodiment is not limited thereto.

Fig. 17A schematically shows an external perspective view of a conventional cellular phone 4000A, and Fig. 17B shows an external perspective view of the cellular phone 4000B according to the embodiment.

The conventional cellular phone 4000A shown in Fig. 17A has a speaker 4100 for transmitting a first sound signal and a receiver 4200 for receiving a second sound signal from the outside. Therefore, the existing cellular phone 4000A must provide a hole for the speaker 4100 and the receiver 4200. [ Particularly, when the receiver 4200 is disposed on the bezel, the cellular phone 4000A necessarily requires a bezel, which limits the degree of freedom of design.

On the other hand, since the cellular phone 4000B according to the embodiment can transmit the first sound signal 4300 or receive the second sound signal 4300 using the piezoelectric element 1000, Holes for the speaker 4100 and the receiver 4200 become unnecessary. Accordingly, by reducing the width of the bezel, the display display area can occupy almost the entire display surface of the cellular phone 4000B, thereby realizing a high-output speaker with high design freedom.

Particularly, in the case of the cellular phone 4000B, the internal space is narrow. In the case of removing the holes, the display portion should be used as a diaphragm, and the vibrating element should also be attached in a thin form, and thus a plate-shaped piezoelectric element is required. At least one of the diaphragm of the speaker used in the existing hall and the rigidity, the elasticity or the mass of the display serving as the diaphragm are different, and the display requires more vibrational force in order to generate vibration relative to the conventional diaphragm .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood that various modifications and applications are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

10, 1000, 1400, 1410, 1420, 1900: piezoelectric element 20, 200: internal electrode
30, 100: piezoelectric part 120: first adhesive layer
300: external electrode 310: first external electrode
320: second external electrode 400: protective portion
410: first protection part 420: second protection part
1100: cover member 1200A, 1200B:
1300: second adhesive layer 1500: back plate
1600: diaphragm 1610: third adhesive layer
1700: Fixing plate 1800: Mass part
2000A, 2000B, 2000C: Piezoelectric actuators
2500: drive control section 2610, 2620: wiring
3000: Piezoelectric module 4000A, 4000B: Mobile phone
4100: speaker 4200: receiver

Claims (16)

A piezoelectric part having a height, a lateral width larger than the height, and a longitudinal width larger than the lateral width, the piezoelectric part having a plate shape;
A plurality of internal electrodes arranged in parallel within the piezoelectric portion and spaced apart in the longitudinal direction;
An external electrode disposed on a side surface of the piezoelectric portion defined by the height and the vertical width; And
And a protective portion covering the piezoelectric portion and the external electrode,
The polarization direction and the longitudinal direction of the piezoelectric portion coincide with each other,
Wherein the acoustic signal is transmitted through one surface of the piezoelectric portion defined by the lateral width and the vertical width. 2. The plasma display panel as claimed in claim 1,
A first external electrode disposed on one side of the side surface of the piezoelectric portion; And
And a second external electrode disposed on the other side of the side surface of the piezoelectric portion opposite to the one side surface. 3. The plasma display panel of claim 2, wherein the plurality of internal electrodes
A first internal electrode and a second internal electrode which are mutually alternately and repeatedly arranged apart from each other in the longitudinal direction of the piezoelectric portion,
The length in the direction of the transverse axis of each of the first and second internal electrodes is smaller than the width,
The first internal electrode is exposed to the one side surface of the piezoelectric portion and is electrically connected to the first external electrode,
And the second internal electrode is exposed to the other side surface of the piezoelectric portion and is electrically connected to the second external electrode. The piezoelectric device according to claim 3, wherein the piezoelectric portion
A plurality of unit blocks stacked in the polarization direction, each of the unit blocks including the plurality of internal electrodes and including a ceramic piezoelectric material; And
And a first adhesive layer for bonding adjacent unit blocks among the plurality of unit blocks. 5. The apparatus of claim 4, wherein each of the plurality of unit blocks
A dummy portion disposed between the inner electrode closest to the first adhesive layer and the first adhesive layer among the plurality of inner electrodes; And
And a polarized portion disposed between the first and second internal electrodes. The method of claim 5, wherein the plurality of internal electrodes
A first dummy electrode exposed on the other side of the piezoelectric portion, spaced apart from the first internal electrode, and arranged on the same line as the first internal electrode; And
And a second dummy electrode exposed on the one side surface of the piezoelectric portion and spaced apart from the second internal electrode and arranged on the same line as the second internal electrode. The method as claimed in claim 5 or 6, wherein the plurality of inner electrodes
Further comprising third and fourth dummy electrodes disposed on the same and separated from each other on the one side surface and the other side surface of the piezoelectric portion in the dummy portion. The piezoelectric element according to claim 7, wherein, in the transverse direction, the length of each of the first, second, third and fourth dummy electrodes is smaller than the length of the internal electrode. 6. The liquid crystal display according to claim 5, wherein, in the longitudinal axis direction, the length of the first adhesive layer is smaller than the length of the polarized portion,
And the length of the dummy portion is smaller than the length of the polarized portion in the longitudinal direction. The method according to claim 9, wherein the length of the first adhesive layer in the longitudinal direction is 0 to 20 mu m or less,
The length of the dummy portion in the direction of the longitudinal axis is 10 占 퐉 to 50 占 퐉,
And the length of the polarized portion in the longitudinal direction is 20 占 퐉 to 100 占 퐉. A first piezoelectric element;
A display unit disposed on the first piezoelectric element;
A second adhesive layer disposed between the first piezoelectric element and the display portion; And
And a cover member disposed on the display unit,
The first piezoelectric element
A piezoelectric part having a height, a lateral width larger than the height, and a longitudinal width larger than the lateral width, the piezoelectric part having a plate shape;
A plurality of internal electrodes arranged in parallel within the piezoelectric portion and spaced apart in the longitudinal direction;
An external electrode disposed on a side surface of the piezoelectric portion defined by the height and the vertical width; And
And a protective portion covering the piezoelectric portion and the external electrode,
The polarization direction and the longitudinal direction of the piezoelectric portion coincide with each other,
Wherein the piezoelectric actuator transmits the first acoustic signal through one surface of the piezoelectric portion defined by the lateral width and the vertical width. 12. The image pickup apparatus according to claim 11, further comprising a second piezoelectric element for outputting an electric signal generated in response to the second acoustic signal,
Wherein the longitudinal axis direction and the polarization direction of the second piezoelectric element cross each other. 12. The piezoelectric actuator according to claim 11, further comprising a back plate disposed between the second adhesive layer and the display unit to protect the display unit. 12. The piezoelectric actuator according to claim 11, wherein the piezoelectric actuator
A diaphragm disposed below the piezoelectric element;
A fixing plate disposed under one end of both ends of the diaphragm; And
And a third adhesive layer for bonding the piezoelectric element to the diaphragm. 15. The piezoelectric actuator according to claim 14, further comprising a mass portion disposed below the other end of both ends of the vibration plate. Piezoelectric actuators; And
And a drive control section for driving the piezoelectric actuator,
The piezoelectric actuator
A piezoelectric element;
A display unit disposed on the piezoelectric element;
A second adhesive layer disposed between the piezoelectric element and the display unit; And
And a cover member disposed on the display unit,
The piezoelectric element
A piezoelectric part having a height, a lateral width larger than the height, and a longitudinal width larger than the lateral width, the piezoelectric part having a plate shape;
A plurality of internal electrodes arranged in parallel within the piezoelectric portion and spaced apart in the longitudinal direction;
An external electrode disposed on a side surface of the piezoelectric portion defined by the height and the vertical width; And
And a protective portion covering the piezoelectric portion and the external electrode,
The polarization direction and the longitudinal direction of the piezoelectric portion coincide with each other,
And transmits the acoustic signal through one surface of the piezoelectric portion defined by the lateral width and the vertical width.

Images