TW202320366A

TW202320366A - Piezoelectric device and piezoelectric speaker

Info

Publication number: TW202320366A
Application number: TW111135535A
Authority: TW
Inventors: 香川裕介
Original assignee: 日商富士軟片股份有限公司
Priority date: 2021-09-24
Filing date: 2022-09-20
Publication date: 2023-05-16
Also published as: WO2023048022A1

Abstract

The present invention addresses the problem of providing: a piezoelectric element in which a piezoelectric film is folded over and laminated, and which is capable of preventing breakage of electrode layers or the like in the folded-over sections when pressure is applied; and a piezoelectric speaker using this piezoelectric element. This problem is solved by satisfying "L ≥ 50 * t" when an adhesion layer which is laminated and adhered to the neighboring piezoelectric film, t denotes the thickness of the adhesion layer at the thickest section of the piezoelectric element, and L is the shortest distance between the folded-over section of the piezoelectric film and the thickest section of the piezoelectric element.

Description

壓電元件及壓電揚聲器Piezoelectric elements and piezoelectric speakers

本發明有關一種壓電元件及使用該壓電元件之壓電揚聲器。The present invention relates to a piezoelectric element and a piezoelectric speaker using the piezoelectric element.

藉由與各種物品接觸並安裝來使物品振動並發出聲音之所謂激發器（激子）被利用於各種用途。例如，若在辦公室中，進行現場發表和電話會議等時，藉由在會議桌、白板及屏幕等安裝激發器而能夠輸出聲音來代替揚聲器。在汽車等車輛中，能夠藉由在控制台、A柱及天花板等中安裝激發器而發出引導音、警告音及音樂等。又，如混合車及電動汽車那樣，在不發出引擎音之汽車之情況下，藉由在保險桿等中安裝激發器而能夠從保險桿等中發出車輛接近通知音。 A so-called exciter (exciton) that vibrates and emits sound by being attached to various objects is used for various purposes. For example, in the office, when conducting on-site presentations and conference calls, etc., by installing exciters on conference tables, whiteboards, and screens, sound can be output instead of speakers. In vehicles such as automobiles, guide sounds, warning sounds, music, etc. can be emitted by installing exciters in consoles, A-pillars, ceilings, and the like. Also, in the case of a car that does not emit engine sound, such as a hybrid car or an electric car, the vehicle approach notification sound can be emitted from the bumper or the like by installing an exciter in the bumper or the like.

在這種激發器中，作為產生振動之可變元件，已知有線圈和磁鐵的組合、以及偏心馬達及線性共振馬達等振動馬達等。該等可變元件難以薄型化。尤其，關於振動馬達存在如下難點：為了增加振動力而需要增加質量體、用於調節振動態程度之頻率調變較難且響應速度慢等。 In such an exciter, known variable elements that generate vibration include combinations of coils and magnets, vibration motors such as eccentric motors and linear resonance motors, and the like. It is difficult to reduce the thickness of these variable elements. In particular, the vibration motor has the following difficulties: in order to increase the vibration force, it is necessary to increase the mass body, and the frequency modulation for adjusting the vibration level is difficult and the response speed is slow.

另一方面，近年來，例如，依據對應於具有撓性之顯示器的要求等，對揚聲器亦要求具有撓性。然而，這種由激發器及振動板組成之構成難以與具有撓性之揚聲器匹配。On the other hand, in recent years, for example, a speaker has been required to be flexible, for example, in response to a demand for a display having flexibility. However, it is difficult to match such a structure composed of exciter and vibrating plate with a flexible speaker.

還考慮到藉由在具有撓性之振動板上黏貼具有撓性之激發器來設為具有撓性之揚聲器。例如，在專利文獻1中，記載有一種積層壓電元件，其積層了複數層用2個薄膜電極夾持了壓電體層之壓電膜。該積層壓電元件中的壓電膜係沿厚度方向極化者，進而，與相鄰之壓電膜的極化方向相反。該積層壓電元件藉由與壓電膜通電而壓電膜沿面方向伸縮。因此，能夠實現如下壓電揚聲器：藉由將該積層壓電元件黏貼於振動板來作為激發器，並且藉由所積層之壓電膜的伸縮運動而振動板彎曲並在與板面正交之方向上振動，從而振動板輸出聲音。 It is also conceivable to provide a flexible speaker by affixing a flexible exciter to a flexible diaphragm. For example, Patent Document 1 describes a laminated piezoelectric element in which a plurality of piezoelectric films are laminated with piezoelectric layers sandwiched between two thin-film electrodes. The piezoelectric film in this multilayer piezoelectric element is polarized in the thickness direction, and furthermore, the polarization direction of the adjacent piezoelectric film is opposite. In this multilayer piezoelectric element, the piezoelectric film expands and contracts in the plane direction when the piezoelectric film is energized. Therefore, it is possible to realize a piezoelectric speaker in which the laminated piezoelectric element is attached to the vibration plate as an exciter, and the vibration plate is bent by the expansion and contraction movement of the laminated piezoelectric film and is perpendicular to the plate surface. Vibrates in the direction so that the vibrating plate outputs sound.

[專利文獻1] 國際公開第2020/095812號[Patent Document 1] International Publication No. 2020/095812

在如專利文獻1那樣的積層壓電元件中，作為積層壓電膜的方法之一，亦如專利文獻1中所記載的那樣，考慮藉由將壓電膜折返成波紋管形狀來積層複數層壓電膜之方法。在積層了複數張切割片狀的壓電膜之情況下，需要對每一個壓電膜連接電極層和電源等的外部裝置。相對於此，在藉由折返壓電膜而積層了複數層之情況下，壓電膜為1張，因此電極層與電源等的外部裝置的連接為1處即可。 In the laminated piezoelectric element such as Patent Document 1, as one of the methods of laminating piezoelectric films, as described in Patent Document 1, it is conceivable to laminate a plurality of layers by folding the piezoelectric film back into a bellows shape. Method of Piezoelectric Film. When a plurality of diced sheet-shaped piezoelectric films are laminated, it is necessary to connect external devices such as an electrode layer and a power supply to each piezoelectric film. On the other hand, when a plurality of layers are laminated by folding back the piezoelectric film, since there is one piezoelectric film, only one connection between the electrode layer and an external device such as a power supply is required.

然而，在將積層壓電元件用作激發器之情況下，如上所述，需要將積層壓電元件黏貼於振動板。積層壓電元件與振動板的黏貼例如經由黏著劑等黏貼劑來將積層壓電元件按壓到振動板來進行。 However, in the case of using a multilayer piezoelectric element as an actuator, as described above, it is necessary to stick the multilayer piezoelectric element to a vibrating plate. The bonding of the multilayer piezoelectric element and the vibration plate is performed by pressing the multilayer piezoelectric element to the vibration plate with an adhesive such as an adhesive, for example.

其中，在折返壓電膜而積層之積層壓電元件中，藉由此時的按壓而對壓電膜施加表面壓力。若該表面壓力施加到壓電膜的折返部，則對壓電膜施加負擔，依據情況，在折返部中，具有導致電極層和/或壓電體層斷裂之問題。Among them, in the multilayer piezoelectric element in which the piezoelectric film is folded and laminated, surface pressure is applied to the piezoelectric film by pressing at this time. When this surface pressure is applied to the folded portion of the piezoelectric film, a load is applied to the piezoelectric film, and there is a problem of causing breakage of the electrode layer and/or the piezoelectric body layer in the folded portion in some cases.

又，在專利文獻1中所記載之積層壓電元件中，壓電膜例如使用將壓電體粒子分散於高分子材料而成之高分子複合壓電體來用作壓電體層。因此，該積層壓電元件具有非常好的撓性。故，藉由將該積層壓電元件黏貼於具有撓性之振動板而能夠實現具有撓性且能夠折彎及捲取之壓電揚聲器。其中，在捲取振動板時，積層壓電元件亦與振動板一起捲取，但在進行該捲取時，與之前相同，對折返部的壓電膜施加表面壓力，依據情況導致電極層和/或壓電體層斷裂。 In addition, in the multilayer piezoelectric element described in Patent Document 1, the piezoelectric film uses, for example, a polymer composite piezoelectric material obtained by dispersing piezoelectric particles in a polymer material as the piezoelectric layer. Therefore, the laminated piezoelectric element has very good flexibility. Therefore, by affixing this laminated piezoelectric element to a flexible vibration plate, a flexible piezoelectric speaker capable of being bent and rolled can be realized. However, when winding up the vibration plate, the multilayer piezoelectric element is also wound up together with the vibration plate. However, in this winding, as before, surface pressure is applied to the piezoelectric film at the folded portion, and the electrode layer and /or the piezoelectric body layer is broken.

本發明的目的係為了解決這種先前技術的問題點，提供一種壓電元件及使用該壓電元件之壓電揚聲器，該壓電元件係藉由折返壓電膜而積層之壓電元件，在被施加壓力之情況下，能夠防止電極層等在壓電膜的折返部斷裂。The object of the present invention is to solve the problems of the prior art and provide a piezoelectric element and a piezoelectric speaker using the piezoelectric element. The piezoelectric element is a piezoelectric element laminated by folding a piezoelectric film. When pressure is applied, the electrode layer and the like can be prevented from breaking at the folded portion of the piezoelectric film.

為了實現這種目的，本發明具有以下構成。 [1]一種壓電元件，其藉由折返具有撓性之壓電膜而積層了複數層壓電膜，其特徵在於，壓電元件具有將積層並相鄰之壓電膜進行黏貼之黏貼層，在將壓電元件的最厚部的黏貼層的厚度設為t、將壓電膜的折返部的端部與壓電元件的最厚部的最短距離設為L時，滿足“L≥50*t”。 [2]如[1]所述之壓電元件，其從壓電膜的積層方向觀察時為矩形，矩形的長邊與壓電膜的折返線一致。 [3]如[1]或[2]所述之壓電元件，其中最厚部的厚度為壓電膜的折返部的厚度的115%以上。 [4]如[1]至[3]之任一項所述之壓電元件，其中壓電膜具有壓電體層、設置於壓電體層的兩面之電極層及設置成覆蓋電極層之保護層。 [5]如[4]所述之壓電元件，其中壓電體層是在高分子材料中具有壓電體粒子之高分子複合壓電體。 [6]如[5]所述之壓電元件，其中高分子材料具有氰乙基。 [7]如[6]所述之壓電元件，其中高分子材料是氰乙基化聚乙烯醇。 [8]一種壓電揚聲器，其藉由將[1]至[7]之任一項所述之壓電元件黏貼於在振動板而成。 [發明效果] In order to achieve this object, the present invention has the following constitutions. [1] A piezoelectric element in which a plurality of piezoelectric films are laminated by folding back a flexible piezoelectric film, characterized in that, The piezoelectric element has an adhesive layer for adhering laminated and adjacent piezoelectric films, When t is the thickness of the adhesive layer at the thickest part of the piezoelectric element, and L is the shortest distance between the end of the folded part of the piezoelectric film and the thickest part of the piezoelectric element, "L≥50* t". [2] The piezoelectric element according to [1], which is rectangular when viewed from the lamination direction of the piezoelectric film, The long side of the rectangle coincides with the foldback line of the piezoelectric film. [3] The piezoelectric element described in [1] or [2], wherein The thickness of the thickest part is 115% or more of the thickness of the folded part of the piezoelectric film. [4] The piezoelectric element according to any one of [1] to [3], wherein The piezoelectric film has a piezoelectric layer, electrode layers provided on both surfaces of the piezoelectric layer, and a protective layer provided to cover the electrode layers. [5] The piezoelectric element as described in [4], wherein The piezoelectric layer is a polymer composite piezoelectric body having piezoelectric particles in a polymer material. [6] The piezoelectric element as described in [5], wherein The polymer material has a cyanoethyl group. [7] The piezoelectric element as described in [6], wherein The polymer material is cyanoethylated polyvinyl alcohol. [8] A piezoelectric speaker formed by affixing the piezoelectric element described in any one of [1] to [7] to a vibration plate. [Invention effect]

依據這種本發明，在藉由折返壓電膜而積層之壓電元件中，在被施加壓力之情況下，能夠防止電極層等在壓電膜的折返部斷裂。According to the present invention, in the piezoelectric element laminated by folding back the piezoelectric film, when a pressure is applied, the electrode layer or the like can be prevented from breaking at the folded portion of the piezoelectric film.

以下，關於本發明的壓電元件及壓電揚聲器，基於所添加之圖式中示出之較佳實施態樣，進行詳細說明。Hereinafter, the piezoelectric element and the piezoelectric speaker of the present invention will be described in detail based on preferred embodiments shown in the attached drawings.

以下所記載之構成要件的說明有時基於本發明的代表性實施態樣來進行，但本發明並不限定於該等實施態樣。又，在以下示出之圖為用於說明本發明的壓電元件及壓電揚聲器之示意圖。故，各構件及各部位的大小、厚度、形狀、以及位置關係等與實際物體不同。 The description of the constituent requirements described below may be based on representative embodiments of the present invention, but the present invention is not limited to these embodiments. Moreover, the figure shown below is a schematic diagram for demonstrating the piezoelectric element and piezoelectric speaker of this invention. Therefore, the size, thickness, shape, and positional relationship of each member and each part are different from the actual object.

在本發明中，使用“～”表示之數值範圍係指包含記載於“～”的前後之數值作為下限值及上限值之範圍。進而，在本發明中，附加於電極層及保護層等之第1及第2係指為了方便區別基本相同的2個構件，並且說明本發明的壓電元件及壓電揚聲器而附加者。故，該等構件中的第1及第2並無技術意義，又，與實際使用狀態及相互位置關係等無關。 In the present invention, the numerical range represented by "-" means a range including the numerical values described before and after "-" as the lower limit and the upper limit. Furthermore, in the present invention, first and second added to electrode layers, protective layers, etc. refer to those added for the convenience of distinguishing two members that are basically the same, and for describing the piezoelectric element and piezoelectric speaker of the present invention. Therefore, the first and second of these components have no technical significance, and have nothing to do with the actual use status and mutual positional relationship.

圖1中示意性地示出本發明的壓電元件的一例。另外，在圖1中，分別地將上段表示壓電元件10的前視圖，下段表示俯視圖。另外，前視圖係指，從後述之壓電膜的面方向觀察本發明的壓電元件之圖。又，俯視圖係指，從後述之壓電膜的積層方向觀察本發明的壓電元件之圖。換言之，俯視圖係指，從與壓電膜12的主表面正交之方向觀察壓電元件之圖。主表面係片狀物（薄膜、板狀物、層）的最大面，通常為片狀物的厚度方向的兩面。在以下說明中，為了方便將從與俯視圖相同的方向觀察本發明的壓電元件之情況亦稱為“平面觀察”。又，為了方便，將從平面觀察本發明的壓電元件時的形狀亦即俯視圖中的本發明的壓電元件的形狀亦稱為“平面形狀”。 An example of the piezoelectric element of the present invention is schematically shown in FIG. 1 . In addition, in FIG. 1, the upper row shows the front view of the piezoelectric element 10, and the lower row shows a top view, respectively. In addition, the front view refers to a view of the piezoelectric element of the present invention viewed from the surface direction of the piezoelectric film described later. In addition, the plan view refers to a view of the piezoelectric element of the present invention viewed from the lamination direction of the piezoelectric film described later. In other words, the top view refers to a view in which the piezoelectric element is viewed from a direction perpendicular to the main surface of the piezoelectric film 12 . The main surface is the largest surface of a sheet (film, plate, layer), usually both sides in the thickness direction of the sheet. In the following description, the case where the piezoelectric element of the present invention is viewed from the same direction as the top view is also referred to as "plan view" for convenience. Also, for convenience, the shape of the piezoelectric element of the present invention when viewed from a plan view, that is, the shape of the piezoelectric element of the present invention in a plan view is also referred to as "planar shape".

圖1中示出之壓電元件10係藉由將具有撓性之壓電膜12以波紋管形狀折返複數次而積層複數層壓電膜12者。壓電膜12係分別地在壓電體層26的一面具有第1電極層28、在另一面具有第2電極層30、在第1電極層28的表面設置第1保護層32、在第2電極層30的表面設置第2保護層34者。又，在壓電元件10中，藉由折返而積層並相鄰之壓電膜12藉由黏貼層20來黏貼。 The piezoelectric element 10 shown in FIG. 1 is one in which a plurality of piezoelectric films 12 are laminated by folding a flexible piezoelectric film 12 multiple times in a bellows shape. The piezoelectric film 12 has a first electrode layer 28 on one side of the piezoelectric body layer 26, a second electrode layer 30 on the other side, a first protective layer 32 on the surface of the first electrode layer 28, and a second electrode layer on the second electrode layer. A second protective layer 34 is provided on the surface of the layer 30 . In addition, in the piezoelectric element 10 , the adjacent piezoelectric films 12 laminated by folding are adhered by the adhesive layer 20 .

圖式例的壓電元件10係將矩形（長方形）的壓電膜12以等間隔折返4次而積層5層的壓電膜12者。故，壓電元件10的平面形狀成為矩形。 The piezoelectric element 10 of the illustrated example is a piezoelectric film 12 in which five layers are stacked by folding a rectangular (rectangular) piezoelectric film 12 four times at equal intervals. Therefore, the planar shape of the piezoelectric element 10 becomes a rectangle.

在本發明的壓電元件10中，在折返矩形的壓電膜12之情況下，藉由壓電膜12的折返而形成之折返線在壓電元件10的平面形狀中，可以沿長邊方向一致，亦可以沿短邊方向一致。在以下說明中，為了方便將藉由壓電膜12的折返而形成之折返線亦即折返部的端部外側的頂部的線亦稱為“棱線”。 In the piezoelectric element 10 of the present invention, in the case of folding back the rectangular piezoelectric film 12 , the folding line formed by the folding of the piezoelectric film 12 can extend along the longitudinal direction in the planar shape of the piezoelectric element 10 . Consistent, also can be consistent along the short side direction. In the following description, the folded line formed by the folded back of the piezoelectric film 12 , that is, the top line outside the end of the folded portion is also referred to as a “ridge line” for convenience.

作為一例，以平面形狀為20×5cm的矩形的壓電元件10為例進行說明。如圖2中示意性地表示那樣，本發明的壓電元件10可以係將20×25cm的矩形的壓電膜12沿25cm的邊的方向每以5cm折返而得之棱線為長邊方向的20cm的壓電元件10。或者，如圖3中示意性地表示那樣，本發明的壓電元件10可以係將100×5cm的矩形的壓電膜12沿100cm的邊的方向以20cm折返而得之棱線為短邊方向的5cm的壓電元件10。另外，在圖2及圖3中，省略後述之壓電元件10的最厚部。 As an example, a rectangular piezoelectric element 10 with a planar shape of 20×5 cm will be described as an example. As schematically shown in FIG. 2 , the piezoelectric element 10 of the present invention can be formed by turning a rectangular piezoelectric film 12 of 20 x 25 cm along the direction of the side of 25 cm, and the ridge line obtained by turning back every 5 cm is the long side direction. A piezoelectric element 10 of 20 cm. Alternatively, as schematically shown in FIG. 3 , the piezoelectric element 10 of the present invention may be a ridge line obtained by folding a rectangular piezoelectric film 12 of 100 x 5 cm in the side direction of 100 cm at 20 cm as the short side direction. A piezoelectric element 10 of 5 cm. In addition, in FIGS. 2 and 3 , the thickest part of the piezoelectric element 10 to be described later is omitted.

然而，本發明的壓電元件10係如圖2中示出之平面形狀為矩形並且棱線亦即基於折返的端部的線（折返線）與長邊一致之構成為較佳。藉由設為這種構成，從壓電元件10的製造變得容易、能夠提高生產率、能夠降低折返部（彎曲部）的電流密度等觀點考慮為較佳。 However, it is preferable that the piezoelectric element 10 of the present invention has a rectangular planar shape as shown in FIG. Such a configuration is preferable from the viewpoints of ease of manufacture of the piezoelectric element 10 , improvement of productivity, and reduction of current density at the folded portion (curved portion).

另外，作為較佳態樣，圖1～3中示出之壓電元件10係藉由折返矩形的壓電膜12而製作之平面形狀為矩形者。然而，在本發明的壓電元件中，壓電膜12的形狀不限於矩形，能夠利用各種形狀。作為一例，例示出圓形、圓角長方形（長橢圓形）、橢圓形及六邊形等多邊形等。 In addition, as a preferred mode, the piezoelectric element 10 shown in FIGS. 1 to 3 is manufactured by folding back a rectangular piezoelectric film 12 so that its planar shape is rectangular. However, in the piezoelectric element of the present invention, the shape of the piezoelectric film 12 is not limited to a rectangle, and various shapes can be utilized. As an example, polygons such as a circle, a rounded rectangle (long ellipse), an ellipse, and a hexagon are exemplified.

如上所述，壓電元件10係將壓電膜12折返複數次而積層者。圖式例的壓電元件10藉由折返4次壓電膜12而積層5層的壓電膜12。又，積層並相鄰之壓電膜12藉由黏貼層20而黏貼。本發明的壓電元件10藉由以這種方式積層複數個壓電膜12並黏貼相鄰之壓電膜12，與使用了1張壓電膜之情況相比，能夠增加作為壓電元件的伸縮力。其結果，例如，能夠使後述之振動板以較大的力彎曲，並輸出高音壓的聲音。又，本發明的壓電元件10在將壓電元件在最厚的位置亦即最厚部M的黏貼層20的厚度設為t、最厚部M與棱線亦即壓電膜12的折返部的端部的最短距離設為L時，滿足“L≥50*t”。本發明的壓電元件10藉由具有這種構成，在如與後述之振動板黏貼時等那樣，在壓電元件沿積層方向被加壓時，能夠防止壓電體層26及電極層在壓電膜12的折返部斷裂。關於這一點，在後面進行詳細敘述。 As described above, the piezoelectric element 10 is laminated by folding the piezoelectric film 12 a plurality of times. In the piezoelectric element 10 of the illustrated example, five piezoelectric films 12 are laminated by folding the piezoelectric film 12 four times. Also, the piezoelectric films 12 stacked and adjacent to each other are bonded by the bonding layer 20 . In the piezoelectric element 10 of the present invention, by laminating a plurality of piezoelectric films 12 and adhering adjacent piezoelectric films 12 in this way, compared with the case of using one piezoelectric film, the number of piezoelectric elements can be increased. Stretch force. As a result, for example, the diaphragm to be described later can be bent with a large force to output high sound pressure sound. In addition, in the piezoelectric element 10 of the present invention, the thickness of the adhesive layer 20 at the thickest part of the piezoelectric element, that is, the thickest part M, is set to t, and the foldback of the thickest part M and the ridge line, that is, the piezoelectric film 12 When L is the shortest distance between the ends of the portion, “L≧50*t” is satisfied. Since the piezoelectric element 10 of the present invention has such a structure, it is possible to prevent the piezoelectric layer 26 and the electrode layer from being damaged by piezoelectricity when the piezoelectric element is pressurized in the stacking direction, such as when the piezoelectric element is attached to a vibrating plate described later. The folded portion of the film 12 is broken. This point will be described in detail later.

在本發明的壓電元件10中，壓電元件10中的壓電膜12的積層數並不限於圖式例的5層。亦即，在本發明的壓電元件10可以係積層將壓電膜12折返3次以下之4層以下的壓電膜12者，或者係積層將壓電膜12折返5次以上之6層以上的壓電膜12者。在本發明的壓電元件中，壓電膜12的積層數並無限制，2～10層為較佳，3～7層為更佳。 In the piezoelectric element 10 of the present invention, the number of layers of the piezoelectric film 12 in the piezoelectric element 10 is not limited to five layers as shown in the illustration. That is, in the piezoelectric element 10 of the present invention, the piezoelectric film 12 may be stacked with 4 or less layers of piezoelectric film 12 folded back three times or less, or may be stacked with 6 or more layers of piezoelectric film 12 folded back 5 or more times. 12 of the piezoelectric film. In the piezoelectric element of the present invention, the number of layers of the piezoelectric film 12 is not limited, preferably 2-10 layers, more preferably 3-7 layers.

在壓電元件10中，在藉由折返而積層之壓電膜12中，沿積層方向相鄰之壓電膜12彼此藉由黏貼層20來黏貼。藉由黏貼層20而黏貼在積層方向上相鄰之壓電膜12，能夠直接傳遞各壓電膜12的伸縮，作為積層了壓電膜12之積層體，能夠無浪費地驅動。 In the piezoelectric element 10 , among the piezoelectric films 12 laminated by folding back, the piezoelectric films 12 adjacent in the lamination direction are adhered to each other by the adhesive layer 20 . Adhering the adjacent piezoelectric films 12 in the stacking direction with the adhesive layer 20 can directly transmit the expansion and contraction of each piezoelectric film 12, and can be driven without waste as a laminated body on which the piezoelectric films 12 are stacked.

在本發明中，若能夠黏貼相鄰之壓電膜12，則黏貼層20能夠利用各種公知的黏貼劑（黏貼材料）。故，黏貼層20可以係由接著劑（接著材料）組成之層，亦可以係由黏著劑（黏著材料）組成之層，亦可以係由具有接著劑和黏著劑雙方的特徵之材料組成之層。另外，接著劑係指，在貼合時具有流動性，然後成為固體之黏貼劑。又，黏著劑係指，在貼合時為凝膠狀（橡膠狀）的柔軟的固體，然後凝膠狀的狀態亦不變化之黏貼劑。又，黏貼層20可以係藉由塗佈液體等具有流動性之黏貼劑而形成者，亦可以係使用薄片狀的黏貼劑而形成者。 In the present invention, as long as the adjacent piezoelectric films 12 can be bonded, various known adhesives (adhesive materials) can be used for the adhesive layer 20 . Therefore, the adhesive layer 20 may be a layer composed of an adhesive (adhesive material), may also be a layer composed of an adhesive (adhesive material), or may be a layer composed of a material having the characteristics of both the adhesive and the adhesive. . In addition, the adhesive refers to an adhesive that has fluidity when pasted and then becomes solid. In addition, the adhesive refers to an adhesive that is a gel-like (rubber-like) soft solid at the time of bonding, and the gel-like state does not change after that. In addition, the adhesive layer 20 may be formed by applying a fluid adhesive such as a liquid, or may be formed using a sheet-like adhesive.

其中，壓電元件10作為一例，用作激發器。亦即，關於壓電元件10，藉由使所積層之複數張壓電膜12伸縮而自身伸縮，例如如後述使振動板62彎曲並振動而發出聲音。故，在壓電元件10中，所積層之各壓電膜12的伸縮直接被傳遞為較佳。若在壓電膜12之間存在如緩和振動之具有黏性之物質，則會導致壓電膜12的伸縮能量的傳遞效率變低而導致壓電元件10的驅動效率降低。若考慮到這一點，則黏貼層20係相比由黏著劑組成之黏著劑層，可獲得固態且較硬的黏貼層20之由接著劑組成之接著劑層為較佳。作為更佳的黏貼層20，具體而言，可較佳地例示出由聚酯系接著劑及苯乙烯·丁二烯橡膠（SBR）系接著劑等熱塑性類型的接著劑組成之黏貼層。接著與黏著不同，在要求高接著溫度時有用。又，熱塑性類型的接著劑兼備“相對低溫、短時間及強接著”，因此為較佳。 Among them, the piezoelectric element 10 is used as an actuator as an example. That is, the piezoelectric element 10 expands and contracts itself by expanding and contracting the plurality of stacked piezoelectric films 12 , for example, bending and vibrating the vibrating plate 62 as will be described later to generate sound. Therefore, in the piezoelectric element 10, it is preferable that the expansion and contraction of the laminated piezoelectric films 12 be directly transmitted. If there is a viscous substance between the piezoelectric films 12 to dampen the vibration, the transmission efficiency of the expansion and contraction energy of the piezoelectric film 12 will be lowered, and the driving efficiency of the piezoelectric element 10 will be lowered. In consideration of this point, the adhesive layer 20 is preferably an adhesive layer composed of an adhesive that can obtain a solid and relatively hard adhesive layer 20 rather than an adhesive layer composed of an adhesive. As the more preferable adhesive layer 20 , specifically, an adhesive layer composed of a thermoplastic adhesive such as a polyester-based adhesive and a styrene-butadiene rubber (SBR)-based adhesive can be preferably exemplified. Adhesion is different from adhesion, and it is useful when high adhesion temperature is required. In addition, thermoplastic type adhesives are preferred because they have both "relatively low temperature, short time and strong adhesion".

在壓電元件10中，黏貼層20的厚度並無限制，只要依據黏貼層20的形成材料，適當設定能夠顯現充分的黏貼力之厚度即可。其中，關於壓電元件10，黏貼層20越薄越提高壓電體層26的伸縮能量（振動能量）的傳遞效果，能夠提高能量效率。又，若黏貼層20厚且剛性高，則有時可能會限制壓電膜12的伸縮。若考慮到這一點，則黏貼層20薄於壓電體層26為較佳。亦即，在壓電元件10中，黏貼層20硬且薄為較佳。具體而言，黏貼層20的厚度係黏貼後的厚度為0.1～50μm為較佳，0.1～30μm為更佳，0.1～10μm為進一步較佳。 In the piezoelectric element 10 , the thickness of the adhesive layer 20 is not limited, as long as the thickness can be appropriately set to exhibit sufficient adhesive force according to the forming material of the adhesive layer 20 . Among them, regarding the piezoelectric element 10 , the thinner the adhesive layer 20 is, the better the transmission effect of the expansion and contraction energy (vibration energy) of the piezoelectric layer 26 is, and energy efficiency can be improved. Also, if the adhesive layer 20 is thick and rigid, expansion and contraction of the piezoelectric film 12 may be restricted. Taking this point into consideration, it is preferable that the adhesive layer 20 is thinner than the piezoelectric layer 26 . That is, in the piezoelectric element 10, the adhesive layer 20 is preferably hard and thin. Specifically, the thickness of the adhesive layer 20 after pasting is preferably 0.1-50 μm, more preferably 0.1-30 μm, and even more preferably 0.1-10 μm.

在本發明的壓電元件中，壓電膜12只要係能夠彎曲和拉伸之具有撓性者，則能夠利用各種公知的壓電膜12。另外，本發明中，具有撓性係指與一般解釋為具有撓性之含義相同，表示能夠彎曲及能夠繞曲，具體而言，在不發生破壞和損傷之狀態下，能夠彎曲和拉伸。 In the piezoelectric element of the present invention, various known piezoelectric films 12 can be used as long as the piezoelectric film 12 is flexible and can be bent and stretched. In addition, in the present invention, "having flexibility" means being able to bend and bend, specifically, being able to bend and stretch without causing damage or damage.

在本發明的壓電元件10中，壓電膜12作為較佳態樣，具有設置於壓電體層26的兩面之電極層及包覆電極層而設置之保護層。圖4中利用剖面圖示意性地表示壓電膜12的一例。在圖4等中，為了簡化圖式來清楚地示出構成，將省略陰影線。另外，在以下說明中，若沒有特別說明，則“截面”表示壓電膜的厚度方向的截面。壓電膜的厚度方向係壓電膜的積層方向。 In the piezoelectric element 10 of the present invention, the piezoelectric film 12 preferably has an electrode layer provided on both surfaces of the piezoelectric layer 26 and a protective layer provided to cover the electrode layer. An example of the piezoelectric film 12 is schematically shown in FIG. 4 with a cross-sectional view. In FIG. 4 and the like, hatching is omitted in order to simplify the drawing and clearly show the configuration. In addition, in the following description, unless otherwise specified, "cross-section" means a cross-section in the thickness direction of the piezoelectric film. The thickness direction of the piezoelectric film is the lamination direction of the piezoelectric film.

如圖4所示那樣，圖式例的壓電膜12具有壓電體層26、積層於壓電體層26的一個面之第1電極層28、積層於第1電極層28之第1保護層32、積層於壓電體層26的另一個面之第2電極層30、積層於第2電極層30之第2保護層34。As shown in FIG. 4 , the piezoelectric film 12 of the illustrated example has a piezoelectric layer 26 , a first electrode layer 28 laminated on one surface of the piezoelectric layer 26 , and a first protective layer 32 laminated on the first electrode layer 28 . , the second electrode layer 30 laminated on the other surface of the piezoelectric layer 26 , and the second protective layer 34 laminated on the second electrode layer 30 .

如上所述，本發明的壓電元件10藉由折返1張壓電膜12而積層壓電膜12。因此，即便積層了複數張壓電膜12，但用於處進行用於驅動壓電元件10亦即壓電膜12之電極的引出，能夠在後述之各電極層設置一處。其結果，能夠簡化壓電元件10的構成及電極佈線，進而，生產率亦優異。又，由於藉由折返1張壓電膜12，藉由積層而相鄰之壓電膜彼此對向之電極層成為相同極性，因此即使電極層彼此接觸亦不發生短路。 As described above, in the piezoelectric element 10 of the present invention, the piezoelectric film 12 is laminated by folding one piezoelectric film 12 back. Therefore, even if a plurality of piezoelectric films 12 are laminated, one location for drawing electrodes for driving the piezoelectric element 10 , that is, the piezoelectric film 12 , can be provided in each electrode layer described later. As a result, the configuration and electrode wiring of the piezoelectric element 10 can be simplified, and the productivity is also excellent. In addition, since one piezoelectric film 12 is folded back, the electrode layers of adjacent piezoelectric films facing each other become the same polarity by lamination, and thus no short circuit occurs even if the electrode layers are in contact with each other.

在壓電膜12中，壓電體層26能夠利用各種公知的壓電體層。在壓電膜12中，如圖4中示意性地表示那樣，壓電體層26係在包含高分子材料之高分子基質38中包含壓電體粒子40之高分子複合壓電體為較佳。 In the piezoelectric film 12 , various known piezoelectric layers can be used for the piezoelectric layer 26 . In the piezoelectric film 12, as schematically shown in FIG. 4, the piezoelectric layer 26 is preferably a polymer composite piezoelectric body including piezoelectric particles 40 in a polymer matrix 38 including a polymer material.

其中，高分子複合壓電體（壓電體層26）為具備以下用件者為較佳。另外，本發明中，常溫係指0～50℃。（i）撓性例如，以作為可攜式如報紙或雜誌之類的文件感覺緩慢彎曲之狀態進行把持之情況下，從外部不斷受到數Hz以下的比較緩慢且較大的彎曲變形。此時，若高分子複合壓電體硬，則有產生其相對程度之較大的彎曲應力而在高分子基質與壓電體粒子的界面產生龜裂，最終導致破壞之虞。故，對高分子複合壓電體要求適當的柔軟性。又，若能夠將應變能作為熱向外部擴散，則能夠緩和應力。故，要求高分子複合壓電體的損耗正切適當大。（ii）音質揚聲器以20Hz～20kHz的音頻頻帶的頻率振動壓電體粒子，並藉由其振動能量使振動板（高分子複合壓電體）整體一體地振動以再現聲音。故，為了提高振動能量的傳遞效率，對高分子複合壓電體要求適當的硬度。又，若揚聲器的頻率特性平滑，則隨著曲率的變化而最低共振頻率f ₀變化時之音質的變化量亦減小。故，要求高分子複合壓電體的損耗正切適當大。 Among them, it is preferable that the polymer composite piezoelectric body (piezoelectric body layer 26 ) has the following requirements. In addition, in this invention, normal temperature means 0-50 degreeC. (i) Flexibility For example, when a portable document such as a newspaper or a magazine is held in a state where it feels like it is being bent slowly, a relatively slow and large bending deformation of several Hz or less is continuously received from the outside. At this time, if the polymer composite piezoelectric body is hard, a relatively large bending stress may be generated to cause cracks at the interface between the polymer matrix and the piezoelectric body particles, which may eventually lead to destruction. Therefore, appropriate flexibility is required for the polymer composite piezoelectric body. Also, if strain energy can be diffused to the outside as heat, stress can be relaxed. Therefore, the loss tangent of the polymer composite piezoelectric body is required to be appropriately large. (ii) Acoustic quality The speaker vibrates piezoelectric particles at a frequency in the audio frequency range of 20 Hz to 20 kHz, and the vibrating energy vibrates the vibration plate (polymer composite piezoelectric body) as a whole to reproduce sound. Therefore, in order to improve the transmission efficiency of vibration energy, appropriate hardness is required for the polymer composite piezoelectric body. Also, if the frequency characteristics of the speaker are smooth, the amount of change in sound quality when the lowest resonance frequency f ₀ changes with changes in the curvature is also small. Therefore, the loss tangent of the polymer composite piezoelectric body is required to be appropriately large.

眾所周知，揚聲器用振動板的最低共振頻率f ₀由下述式給出。其中，s為振動系統的剛性，m為質量。 [數式1]

此時，由於壓電膜的彎曲程度亦即彎曲部的曲率半徑變得越大，則機械剛性s下降，因此最低共振頻率f ₀變小。亦即，有時依據壓電膜的曲率半徑而揚聲器的音質（音量、頻率特性）改變。 As is well known, the lowest resonance frequency f ₀ of a speaker diaphragm is given by the following equation. Among them, s is the rigidity of the vibration system, and m is the mass. [Formula 1]

At this time, as the degree of curvature of the piezoelectric film, that is, the radius of curvature of the bent portion increases, the mechanical rigidity s decreases, and therefore the minimum resonance frequency f ₀ decreases. That is, the sound quality (volume, frequency characteristics) of the speaker may change depending on the curvature radius of the piezoelectric film.

綜上所述，要求高分子複合壓電體對於20Hz～20kHz的振動表現堅硬，而對於數Hz以下的振動表現柔軟。又，要求相對於20kHz以下的所有頻率的振動，高分子複合壓電體的損耗正切適當大。To sum up, it is required that the polymer composite piezoelectric body exhibits rigidity for vibrations of 20 Hz to 20 kHz and softness for vibrations of several Hz or less. In addition, the loss tangent of the polymer composite piezoelectric body is required to be appropriately large with respect to vibrations at all frequencies below 20 kHz.

通常，高分子固體具有黏彈性緩和機構，並隨著溫度的上升或者頻率的下降，大規模的分子運動作為儲存彈性係數（楊氏模量）的下降（緩和）或者損失彈性係數的極大化（吸收）而被觀察到。其中，藉由非晶質區域的分子鏈的微布朗（Micro Brownian）運動引起之緩和被稱作主分散，可觀察到非常大的緩和現象。該主分散產生之溫度為玻璃轉移點（Tg），黏彈性緩和機構最明顯之顯現。在高分子複合壓電體（壓電體層26）中，藉由將玻璃轉移點在常溫下之高分子材料，換言之，在常溫下具有黏彈性之高分子材料用於基質中，實現對於20Hz～20kHz的振動較硬地動作，對於數Hz以下的慢振動較軟地動作之高分子複合壓電體。尤其，從較佳地顯現該動作等方面考慮，將頻率1Hz中的玻璃轉移點Tg在常溫下之高分子材料用於高分子複合壓電體的基質中為較佳。 Generally, polymer solids have a viscoelastic relaxation mechanism, and as the temperature increases or the frequency decreases, large-scale molecular motion acts as a decrease (relaxation) in the storage elastic coefficient (Young's modulus) or a maximization of the loss elastic coefficient ( absorption) was observed. Among them, the relaxation caused by the Micro Brownian motion of the molecular chains in the amorphous region is called the main dispersion, and a very large relaxation phenomenon can be observed. The temperature at which the main dispersion occurs is the glass transition point (Tg), where the viscoelastic relaxation mechanism is most evident. In the polymer composite piezoelectric body (piezoelectric body layer 26), by using a polymer material with a glass transition point at room temperature, in other words, a polymer material with viscoelasticity at room temperature, for the matrix, it is possible to achieve a frequency range of 20 Hz to 20 Hz. A polymer composite piezoelectric body that operates hard at vibrations of 20kHz and soft at slow vibrations below a few Hz. In particular, it is preferable to use a polymer material having a glass transition point Tg at room temperature at a frequency of 1 Hz for the matrix of the polymer composite piezoelectric body, from the viewpoint of expressing the motion preferably.

成為高分子基質38之高分子材料在常溫下，基於動態黏彈性試驗的頻率1Hz中的損耗正切Tanδ的極大值為0.5以上為較佳。藉此，高分子複合壓電體藉由外力而被緩慢彎曲時，最大彎曲力矩部中之高分子基質/壓電體粒子的界面的應力集中得到緩和，能夠期待高撓性。 It is preferable that the maximum value of the loss tangent Tanδ at a frequency of 1 Hz based on a dynamic viscoelasticity test of the polymer material used as the polymer matrix 38 is 0.5 or more at room temperature. Thereby, when the polymer composite piezoelectric body is slowly bent by an external force, the stress concentration at the interface of the polymer matrix/piezoelectric body particle in the maximum bending moment portion is alleviated, and high flexibility can be expected.

又，成為高分子基質38之高分子材料如下為較佳，亦即，基於動態黏彈性測量而得之頻率1Hz中的儲存彈性係數（E’）在0℃下為100MPa以上，在50℃下為10MPa以下。藉此，能夠減小高分子複合壓電體藉由外力而被緩慢彎曲時產生之彎曲力矩的同時，能夠對於20Hz～20kHz的音響振動表現堅硬。 In addition, the polymer material used as the polymer matrix 38 is preferably as follows, that is, the storage elastic coefficient (E') at a frequency of 1 Hz based on dynamic viscoelasticity measurement is 100 MPa or more at 0°C, and at 50°C It is below 10MPa. Thereby, the bending moment generated when the polymer composite piezoelectric body is slowly bent by an external force can be reduced, and at the same time, it can be rigid to the acoustic vibration of 20 Hz to 20 kHz.

又，若成為高分子基質38之高分子材料在相對介電常數在25℃下為10以上，則為更佳。藉此，對高分子複合壓電體施加電壓時，對高分子基質中的壓電體粒子需要更高之的電場，因此能夠期待較大的變形量。然而，另一方面，若考慮確保良好的耐濕性等，則相對介電常數在25℃下，高分子材料為10個以下亦為較佳。 Moreover, it is more preferable that the relative permittivity of the polymer material used as the polymer matrix 38 is 10 or more at 25°C. Accordingly, when a voltage is applied to the polymer composite piezoelectric body, a higher electric field is required for the piezoelectric particles in the polymer matrix, and thus a large amount of deformation can be expected. However, on the other hand, in consideration of ensuring good moisture resistance, etc., at 25° C., the number of polymer materials is preferably 10 or less.

作為滿足該等條件之高分子材料，較佳地例示出氰乙基化聚乙烯醇（氰乙基化PVA）、聚乙酸乙烯酯、聚偏二氯乙烯丙烯腈、聚苯乙烯-乙烯基聚異戊二烯嵌段共聚物、聚乙烯基甲基酮及聚甲基丙烯酸丁酯等。又，作為該等高分子材料，亦能夠較佳地利用Hibler 5127（KURARAY CO.,LTD製造）等市售品。 Examples of polymer materials satisfying these conditions include cyanoethylated polyvinyl alcohol (cyanoethylated PVA), polyvinyl acetate, polyvinylidene chloride acrylonitrile, polystyrene-vinyl polyvinyl alcohol, and polystyrene-vinyl polyvinyl alcohol. Isoprene block copolymer, polyvinyl methyl ketone and polybutyl methacrylate, etc. In addition, commercially available items such as Hibler 5127 (manufactured by KURARAY CO., LTD.) can also be preferably used as such polymer materials.

作為構成高分子基質38之高分子材料，使用具有氰乙基之高分子材料為較佳，使用氰乙基化PVA為特佳。亦即，在壓電膜12中，壓電體層26作為高分子基質38而使用具有氰乙基之高分子材料為較佳，使用氰乙基化PVA為特佳。在以下說明中，將以氰乙基化PVA為代表之上述高分子材料亦統稱為“在常溫下具有黏彈性之高分子材料”。 As the polymer material constituting the polymer matrix 38, it is preferable to use a polymer material having a cyanoethyl group, and it is particularly preferable to use cyanoethylated PVA. That is, in the piezoelectric film 12, it is preferable to use a polymer material having a cyanoethyl group as the polymer matrix 38 for the piezoelectric layer 26, and it is particularly preferable to use cyanoethylated PVA. In the following description, the above-mentioned polymer materials represented by cyanoethylated PVA are collectively referred to as "polymer materials having viscoelasticity at room temperature".

另外，該等在常溫下具有黏彈性之高分子材料可以僅使用1種，亦可以併用（混合）使用複數種。In addition, these polymer materials having viscoelasticity at normal temperature may be used alone or in combination (mixed) in plural.

在壓電膜12中，壓電體層26的高分子基質38可以依據需要而併用複數個高分子材料。亦即，以調節介電特性或機械特性等為目的，除在上述常溫下具有黏彈性之高分子材料以外，亦可以依據需要向在構成高分子複合壓電體之高分子基質38添加其他介電性高分子材料。 In the piezoelectric film 12, the polymer matrix 38 of the piezoelectric layer 26 may use a plurality of polymer materials in combination as necessary. That is, for the purpose of adjusting dielectric properties or mechanical properties, etc., in addition to the polymer material having viscoelasticity at the above normal temperature, other dielectric materials can also be added to the polymer matrix 38 constituting the polymer composite piezoelectric body as required. Electrical polymer materials.

作為能夠添加之介電性高分子材料，作為一例，例示出聚偏二氟乙烯、偏二氟乙烯-四氟乙烯共聚物、偏二氟乙烯-三氟乙烯共聚物、聚偏二氟乙烯-三氟乙烯共聚物及聚偏二氟乙烯-四氟乙烯共聚物等氟系高分子、偏二氰乙烯-乙烯酯共聚物、氰乙基纖維素、氰乙基羥基蔗糖、氰乙基羥基纖維素、氰乙基羥基富勒烯、甲基丙烯酸氰乙酯、丙烯酸氰乙酯、氰乙基羥乙基纖維素、氰乙基直鏈澱粉、氰乙基羥丙基纖維素、氰乙基二羥丙基纖維素、氰乙基羥丙基直鏈澱粉、氰乙基聚丙烯醯胺、氰乙基聚丙烯酸乙酯、氰乙基富勒烯、氰乙基聚羥基亞甲基、氰乙基縮水甘油富勒烯、氰乙基蔗糖及氰乙基山梨糖醇等具有氰基或氰乙基之聚合物以及腈橡膠及氯丁二烯橡膠等合成橡膠等。其中，可較佳地利用具有氰乙基之高分子材料。又，在壓電體層26的高分子基質38中，該等介電性高分子材料並不限於1種，亦可以添加複數種。 As dielectric polymer materials that can be added, polyvinylidene fluoride, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, polyvinylidene fluoride- Fluorine-based polymers such as trifluoroethylene copolymer and polyvinylidene fluoride-tetrafluoroethylene copolymer, vinylidene-vinyl ester copolymer, cyanoethyl cellulose, cyanoethyl hydroxy sucrose, cyanoethyl hydroxy fiber cyanoethyl hydroxyfullerene, cyanoethyl methacrylate, cyanoethyl acrylate, cyanoethyl hydroxyethyl cellulose, cyanoethyl amylose, cyanoethyl hydroxypropyl cellulose, cyanoethyl Dihydroxypropyl cellulose, cyanoethyl hydroxypropyl amylose, cyanoethyl polyacrylamide, cyanoethyl polyethylacrylate, cyanoethyl fullerene, cyanoethyl polyhydroxymethylene, cyanide Polymers with cyano or cyanoethyl groups such as ethyl glycidyl fullerene, cyanoethyl sucrose and cyanoethyl sorbitol, and synthetic rubbers such as nitrile rubber and chloroprene rubber. Among them, polymer materials having cyanoethyl groups can be preferably used. In addition, in the polymer matrix 38 of the piezoelectric layer 26, the dielectric polymer material is not limited to one kind, and plural kinds may be added.

又，以調節高分子基質38的玻璃轉移點Tg為目的，除了介電性高分子材料以外，亦可以添加氯乙烯樹脂、聚乙烯、聚苯乙烯、甲基丙烯酸樹脂、聚丁烯及異丁烯等熱塑性樹脂以及酚醛樹脂、脲樹脂、三聚氰胺樹脂、醇酸樹脂及雲母等熱硬化性樹脂等。進而，以提高黏著性為目的，亦可以添加松香酯、松香、萜烯類、萜烯酚及石油樹脂等黏著賦予劑。 In addition, for the purpose of adjusting the glass transition point Tg of the polymer matrix 38, in addition to the dielectric polymer material, vinyl chloride resin, polyethylene, polystyrene, methacrylic resin, polybutylene, isobutylene, etc. may be added. Thermoplastic resins and thermosetting resins such as phenolic resins, urea resins, melamine resins, alkyd resins, and mica. Furthermore, for the purpose of improving the tackiness, tackifiers such as rosin esters, rosin, terpenes, terpene phenols, and petroleum resins may be added.

在壓電體層26的高分子基質38中，在添加除了在常溫下具有黏彈性之高分子材料以外的高分子材料時之添加量並無限制，高分子基質38所佔之比例設為30質量%以下為較佳。藉此，在不損害高分子基質38中的黏彈性緩和機構便能夠發現所添加之高分子材料的特性，因此在高介電率化、耐熱性的提高、與壓電體粒子40或電極層的密接性提高等方面能夠獲得較佳的結果。 In the polymer matrix 38 of the piezoelectric layer 26, there is no limit to the amount of the polymer material other than the polymer material having viscoelasticity at room temperature, and the proportion of the polymer matrix 38 is set to 30% by mass. Below % is better. Thereby, the properties of the added polymer material can be discovered without damaging the viscoelastic relaxation mechanism in the polymer matrix 38, so it is possible to increase the dielectric constant, improve heat resistance, and piezoelectric particles 40 or electrode layers. Better results can be obtained in terms of improved adhesion.

成為壓電體層26之高分子複合壓電體係在這種高分子基質中包含壓電體粒子40者。壓電體粒子40被分散於高分子基質，較佳為被均勻（大致均勻）地分散。壓電體粒子40較佳為由具有鈣鈦礦型或纖鋅礦型的晶體結構之陶瓷粒子組成者。作為構成壓電體粒子40之陶瓷粒子，例如例示出鋯鈦酸鉛（PZT）、鋯鈦酸鉛鑭（PLZT）、鈦酸鋇（BaTiO ₃）、氧化鋅（ZnO）及鈦酸鋇與鐵酸鉍（BiFe ₃）的固體溶液（BFBT）等。 The polymer composite piezoelectric system to be the piezoelectric layer 26 includes piezoelectric particles 40 in such a polymer matrix. The piezoelectric particles 40 are dispersed in the polymer matrix, preferably uniformly (approximately uniformly). The piezoelectric particles 40 are preferably composed of ceramic particles having a perovskite-type or wurtzite-type crystal structure. Examples of ceramic particles constituting piezoelectric particles 40 include lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), barium titanate (BaTiO ₃ ), zinc oxide (ZnO), and barium titanate and iron Bismuth bismuth (BiFe ₃ ) solid solution (BFBT), etc.

壓電體粒子40的粒徑只要依據壓電膜12的尺寸和用途而適當選擇即可。壓電體粒子40的粒徑為1～10μm為較佳。藉由將壓電體粒子40的粒徑設在上述範圍內，在能夠兼顧高壓電特性和撓性等方面能夠獲得較佳的結果。 The particle size of the piezoelectric particles 40 may be appropriately selected according to the size and application of the piezoelectric film 12 . The particle size of the piezoelectric particles 40 is preferably 1 to 10 μm. By setting the particle size of the piezoelectric particles 40 within the above-mentioned range, a favorable result can be obtained in terms of both high piezoelectric characteristics and flexibility.

在壓電膜12中，壓電體層26中的高分子基質38與壓電體粒子40的量比只要依據壓電膜12的面方向的大小及厚度、壓電膜12的用途、壓電膜12中所要求之特性等而適當地設定即可。壓電體層26中的壓電體粒子40的體積分率為30～80%為較佳，50～80%為更佳。藉由將高分子基質38與壓電體粒子40的量比設在上述範圍內，在能夠兼顧高壓電特性和撓性等方面能夠獲得較佳的結果。 In the piezoelectric film 12, the quantitative ratio between the polymer matrix 38 and the piezoelectric particles 40 in the piezoelectric layer 26 depends only on the size and thickness of the piezoelectric film 12 in the plane direction, the application of the piezoelectric film 12, and the piezoelectric film. The characteristics required in 12 can be set appropriately. The volume fraction of the piezoelectric particles 40 in the piezoelectric layer 26 is preferably 30 to 80%, more preferably 50 to 80%. By setting the amount ratio of the polymer matrix 38 to the piezoelectric particles 40 within the above-mentioned range, a good result can be obtained in terms of both high piezoelectric characteristics and flexibility.

又，在壓電膜12中，壓電體層26的厚度並無限制，只要依據壓電膜12的尺寸、壓電膜12的用途、壓電膜12所要求之特性等而適當地設定即可。壓電體層26的厚度為8～300μm為較佳，8～200μm為更佳，10～150μm為進一步較佳，15～100μm為特佳。藉由將壓電體層26的厚度設在上述範圍內，在兼顧剛性的確保和適當的柔軟性等方面能夠獲得較佳的結果。 In addition, in the piezoelectric film 12, the thickness of the piezoelectric layer 26 is not limited, as long as it is appropriately set according to the size of the piezoelectric film 12, the application of the piezoelectric film 12, and the characteristics required for the piezoelectric film 12. . The thickness of the piezoelectric layer 26 is preferably from 8 to 300 μm, more preferably from 8 to 200 μm, still more preferably from 10 to 150 μm, and most preferably from 15 to 100 μm. By setting the thickness of the piezoelectric layer 26 within the above-mentioned range, favorable results can be obtained in terms of ensuring rigidity, appropriate flexibility, and the like.

壓電體層26沿厚度方向極化處理（polarization）為較佳。關於極化處理，在後面進行詳細敘述。The piezoelectric layer 26 is preferably polarized in the thickness direction. The polarization treatment will be described in detail later.

另外，在壓電膜12中，壓電體層26並不限於如上所述那樣，如氰乙基化PVA那樣由在常溫下具有黏彈性之高分子材料組成之高分子基質38中包含壓電體粒子40之高分子複合壓電體。亦即，在壓電膜12中，壓電體層能夠利用各種公知的壓電體層。 In addition, in the piezoelectric film 12, the piezoelectric layer 26 is not limited to that described above, and the polymer matrix 38 composed of a polymer material having viscoelasticity at room temperature such as cyanoethylated PVA contains a piezoelectric material. The particle 40 is a polymer composite piezoelectric body. That is, in the piezoelectric film 12 , various known piezoelectric layers can be used for the piezoelectric layer.

作為一例，在包含上述聚偏二氟乙烯、偏二氯乙烯-四氟乙烯共聚物及偏二氯乙烯-三氟乙烯共聚物等介電性高分子材料之基質中亦能夠利用包含相同的壓電體粒子40之高分子複合壓電體、由聚偏二氟乙烯組成之壓電體層、由除了聚偏二氟乙烯以外的氟樹脂組成之壓電體層、以及積層了由聚L乳酸組成之薄膜和由聚D乳酸組成之薄膜之壓電體層等。然而，如上所述，從可獲得能夠在對於20Hz～20kHz的振動而言動作較硬，對於數Hz以下的較慢的振動而言動作較軟且可獲得優異的音響特性、撓性優異等觀點考慮，在上述之如氰乙基化PVA那樣由在常溫下具有黏彈性之高分子材料組成之高分子基質38中，可較佳地利用包含壓電體粒子40之高分子複合壓電體。 As an example, the same compressive force can also be used in a substrate comprising the above-mentioned dielectric polymer materials such as polyvinylidene fluoride, vinylidene chloride-tetrafluoroethylene copolymer, and vinylidene chloride-trifluoroethylene copolymer. The polymer composite piezoelectric body of the electrode particle 40, the piezoelectric body layer composed of polyvinylidene fluoride, the piezoelectric body layer composed of fluororesin other than polyvinylidene fluoride, and the laminated layer composed of poly-L-lactic acid Films and piezoelectric layers of films composed of poly-D lactic acid, etc. However, as described above, from the viewpoint that it can operate hard for vibrations of 20 Hz to 20 kHz, and can operate softly for slow vibrations of several Hz or less, excellent acoustic characteristics, and excellent flexibility can be obtained. It is considered that in the above-mentioned polymer matrix 38 composed of a polymer material having viscoelasticity at room temperature such as cyanoethylated PVA, a polymer composite piezoelectric body including piezoelectric particles 40 can be preferably used.

圖4中示出之壓電膜12具有：在這種壓電體層26的一面具有第2電極層30，在第2電極層30的表面具有第2保護層34，在壓電體層26的另一個面具有第1電極層28，在第1電極層28的表面具有第1保護層32而成之構成。在壓電膜12中，第1電極層28與第2電極層30形成電極對。換言之，構成壓電膜12之積層薄膜具有由電極對亦即第1電極層28及第2電極層30夾持壓電體層26的兩面，進而由第1保護層32及第2保護層34夾持而成之構成。如此，由第1電極層28及第2電極層30夾持之區域依據所施加之電壓而驅動。 The piezoelectric film 12 shown in FIG. 4 has a second electrode layer 30 on one side of the piezoelectric layer 26, a second protective layer 34 on the surface of the second electrode layer 30, and a second protective layer 34 on the other side of the piezoelectric layer 26. The first electrode layer 28 is provided on one surface, and the first protective layer 32 is provided on the surface of the first electrode layer 28 . In the piezoelectric film 12 , the first electrode layer 28 and the second electrode layer 30 form an electrode pair. In other words, the laminated film constituting the piezoelectric film 12 has both surfaces of the piezoelectric layer 26 sandwiched between the first electrode layer 28 and the second electrode layer 30 as electrode pairs, and further sandwiched by the first protective layer 32 and the second protective layer 34 . The composition of holding. In this way, the region sandwiched between the first electrode layer 28 and the second electrode layer 30 is driven according to the applied voltage.

壓電膜12除了該等層以外，例如，可以具有用於黏貼電極層及壓電體層26之黏貼層及用於黏貼電極層及保護層之黏貼層。黏貼劑可以係接著劑亦可以係黏著劑。又，黏貼劑亦能夠較佳地利用與從壓電體層26去除了壓電體粒子40之高分子材料亦即高分子基質38相同之材料。另外，黏貼層可以在第1電極層28側及第2電極層30側雙方具有，亦可以僅在第1電極層28側及第2電極層30側中的一方具有。 In addition to these layers, the piezoelectric film 12 may have, for example, an adhesive layer for adhering the electrode layer and the piezoelectric layer 26 and an adhesive layer for adhering the electrode layer and the protective layer. The adhesive can be an adhesive or an adhesive. In addition, the same material as the polymer matrix 38 , which is a polymer material from which the piezoelectric particles 40 are removed from the piezoelectric layer 26 , can also be preferably used for the adhesive. In addition, the adhesive layer may be provided on both the first electrode layer 28 side and the second electrode layer 30 side, or may be provided on only one of the first electrode layer 28 side and the second electrode layer 30 side.

在壓電膜12中，第1保護層32及第2保護層34被覆第1電極層28及第2電極層30之同時，起到對壓電體層26賦予適當的剛性和機械強度之作用。亦即，在壓電膜12中，由包含高分子基質38和壓電體粒子40之壓電體層26對於緩慢彎曲變形顯示出非常優異的撓性，但有時依據用途而剛性或機械強度不足。壓電膜12中設置第1保護層32及第2保護層34以彌補該情況。第1保護層32與第2保護層34僅配置位置不同而構成相同。故，在以下說明中，在不需要區別第1保護層32及第2保護層34之情況下，將兩個構件亦統稱為保護層。 In the piezoelectric film 12 , the first protective layer 32 and the second protective layer 34 cover the first electrode layer 28 and the second electrode layer 30 and serve to impart appropriate rigidity and mechanical strength to the piezoelectric layer 26 . That is, in the piezoelectric film 12, the piezoelectric layer 26 including the polymer matrix 38 and the piezoelectric particles 40 exhibits very excellent flexibility against slow bending deformation, but rigidity or mechanical strength may be insufficient depending on the application. . The first protective layer 32 and the second protective layer 34 are provided on the piezoelectric film 12 to compensate for this. The first protective layer 32 and the second protective layer 34 have the same configuration except for the arrangement position. Therefore, in the following description, when there is no need to distinguish the first protective layer 32 and the second protective layer 34, both members are collectively referred to as a protective layer.

保護層並無限制，能夠利用各種片狀物，作為一例，較佳地例示出各種樹脂薄膜。其中，出於具有優異的機械特性及耐熱性等理由，由聚對酞酸乙二酯（PET）、聚丙烯（PP）、聚苯乙烯（PS）、聚碳酸酯（PC）、聚苯硫醚（PPS）、聚甲基丙烯酸甲酯（PMMA）、聚醚醯亞胺（PEI）、聚醯亞胺（PI）、聚醯胺（PA）、聚萘二甲酸乙二酯（PEN）、三乙醯纖維素（TAC）及環狀烯烴系樹脂等組成之樹脂薄膜被較佳地利用。The protective layer is not limited, and various sheets can be used. As an example, various resin films are preferably illustrated. Among them, polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyphenylene sulfide, etc. Ether (PPS), polymethylmethacrylate (PMMA), polyetherimide (PEI), polyimide (PI), polyamide (PA), polyethylene naphthalate (PEN), Resin films composed of triacetyl cellulose (TAC) and cyclic olefin resins are preferably used.

保護層的厚度亦並無限制。又，第1保護層32及第2保護層34的厚度基本上相同，但是亦可以不同。若保護層的剛性過高，則不僅限制壓電體層26的伸縮，亦會損害撓性。因此，除了要求機械強度或作為片狀物的良好的操作性之情況，保護層越薄越有利。 The thickness of the protective layer is also not limited. In addition, the thicknesses of the first protective layer 32 and the second protective layer 34 are basically the same, but may be different. If the rigidity of the protective layer is too high, not only the expansion and contraction of the piezoelectric layer 26 will be restricted, but also the flexibility will be impaired. Therefore, unless mechanical strength or good handleability as a sheet is required, the thinner the protective layer is, the more advantageous it is.

若第1保護層32及第2保護層34的厚度分別在壓電體層26的厚度的2倍以下，則在兼顧剛性的確保與適當的柔軟性等方面可獲得較佳結果。例如，在壓電體層26的厚度為50μm且第1保護層32及第2保護層34由PET組成之情況下，第1保護層32及第2保護層34的厚度分別為100μm以下為較佳，50μm以下為更佳，25μm以下為進一步較佳。 When the thicknesses of the first protective layer 32 and the second protective layer 34 are each less than twice the thickness of the piezoelectric layer 26 , favorable results can be obtained in terms of ensuring rigidity and appropriate flexibility. For example, when the thickness of the piezoelectric layer 26 is 50 μm and the first protective layer 32 and the second protective layer 34 are made of PET, the thicknesses of the first protective layer 32 and the second protective layer 34 are preferably 100 μm or less. , 50 μm or less is more preferable, and 25 μm or less is still more preferable.

另外，在本發明中，第1保護層32及第2保護層34係作為較佳態樣而使用者，並不是必須的構成要件。故，壓電膜12可以係僅具有第1保護層32者，亦可以係僅具有第2保護層34者，亦可以係不具有保護層者。然而，若考慮到壓電膜12的機械強度、電極層的保護性等，則壓電膜至少具有1層保護層為較佳，如圖式例那樣，以覆蓋兩個電極層之方式具有2層的保護層為更佳。 In addition, in this invention, the 1st protective layer 32 and the 2nd protective layer 34 are used as a preferable aspect, and they are not essential components. Therefore, the piezoelectric film 12 may have only the first protective layer 32 , may have only the second protective layer 34 , or may have no protective layer. However, in consideration of the mechanical strength of the piezoelectric film 12, the protective properties of the electrode layers, etc., it is preferable that the piezoelectric film has at least one protective layer. A layer of protection is better.

在壓電膜12中，在壓電體層26與第1保護層32之間設置第1電極層28，在壓電體層26與第2保護層34之間設置第2電極層30。第1電極層28及第2電極層30係用於向壓電體層26施加電壓者。藉由從電極層向壓電體層26施加電壓而伸縮壓電膜12。In the piezoelectric film 12 , the first electrode layer 28 is provided between the piezoelectric layer 26 and the first protective layer 32 , and the second electrode layer 30 is provided between the piezoelectric layer 26 and the second protective layer 34 . The first electrode layer 28 and the second electrode layer 30 are for applying a voltage to the piezoelectric layer 26 . The piezoelectric film 12 expands and contracts by applying a voltage from the electrode layer to the piezoelectric layer 26 .

第1電極層28與第2電極層30除了位置不同以外，基本相同。故，在以下說明中，在不需要區別第1電極層28與第2電極層30之情況下，兩個構件亦統稱為電極層。The first electrode layer 28 and the second electrode layer 30 are basically the same except for the position difference. Therefore, in the following description, when there is no need to distinguish between the first electrode layer 28 and the second electrode layer 30, the two members are also collectively referred to as electrode layers.

在壓電膜中，電極層的形成材料並無限制，能夠利用各種導電體。具體而言，例示出碳、鈀、鐵、錫、鋁、鎳、鉑、金、銀、銅、鉻、鉬、該等的合金、氧化銦錫及PEDOT/PPS（聚乙烯二氧噻吩-聚苯乙烯磺酸）等的導電性高分子等。其中，較佳地例示出銅、鋁、金、銀、鉑及氧化銦錫。其中，從導電性、成本及撓性等觀點考慮，銅為更佳。 In the piezoelectric film, the material for forming the electrode layer is not limited, and various conductors can be used. Specifically, carbon, palladium, iron, tin, aluminum, nickel, platinum, gold, silver, copper, chromium, molybdenum, alloys thereof, indium tin oxide, and PEDOT/PPS (polyethylenedioxythiophene-polyethylene) are exemplified. Styrene sulfonic acid) and other conductive polymers. Among these, copper, aluminum, gold, silver, platinum, and indium tin oxide are preferably exemplified. Among them, copper is more preferable from the viewpoints of conductivity, cost, and flexibility.

又，電極層的形成方法亦並無限制，能夠利用各種真空蒸鍍及濺鍍等氣相沈積法（真空成膜法）或基於電鍍之成膜或者黏貼由上述材料所形成之箔之方法、塗佈之方法等公知的方法。其中，出於能夠確保壓電膜12的撓性等理由，作為電極層，尤其可較佳地利用藉由真空蒸鍍所成膜之銅及鋁的薄膜。其中，特別是較佳地利用基於真空蒸鍍而形成之銅的薄膜。 In addition, the formation method of the electrode layer is not limited, and various vapor deposition methods (vacuum film formation methods) such as vacuum evaporation and sputtering, film formation by electroplating, or a method of adhering foil formed of the above materials can be used. A known method such as a coating method. Among them, for reasons such as ensuring the flexibility of the piezoelectric film 12 , as the electrode layer, especially thin films of copper and aluminum formed by vacuum evaporation can be preferably used. Among them, it is particularly preferable to use a thin film of copper formed by vacuum evaporation.

第1電極層28及第2電極層30的厚度並無限制。又，第1電極28及第2電極30的厚度基本上相同，但是亦可以不同。其中，與上述保護層同樣地，若電極層的剛性過高，則不僅限制壓電體層26的伸縮，亦會損害撓性。因此，若在電阻不會變得過高的範圍內，則電極層越薄越有利。 The thicknesses of the first electrode layer 28 and the second electrode layer 30 are not limited. In addition, the thicknesses of the first electrode 28 and the second electrode 30 are basically the same, but may be different. However, similarly to the above-mentioned protective layer, if the rigidity of the electrode layer is too high, not only the expansion and contraction of the piezoelectric layer 26 is restricted, but also the flexibility is impaired. Therefore, as long as the electrical resistance does not become too high, it is more advantageous for the electrode layer to be thinner.

在壓電膜12中，電極層的厚度與楊氏模量的積低於保護層的厚度與楊氏模量之積，則不會嚴重損害撓性，因此為較佳。例如，例示出第1保護層32及第2保護層34為PET，並且第1電極層28及第2電極層30為銅之情況。此時，PET的楊氏模量約為6.2GPa，銅的楊氏模量約為130GPa。故，若將保護層的厚度設為25μm，則電極層的厚度為1.2μm以下為較佳，0.3μm以下為更佳，其中，設為0.1μm以下為較佳。 In the piezoelectric film 12 , it is preferable that the product of the thickness of the electrode layer and the Young's modulus is lower than the product of the thickness of the protective layer and the Young's modulus since the flexibility will not be seriously impaired. For example, a case where the first protective layer 32 and the second protective layer 34 are PET, and the first electrode layer 28 and the second electrode layer 30 are copper is illustrated. At this time, the Young's modulus of PET is about 6.2 GPa, and the Young's modulus of copper is about 130 GPa. Therefore, if the thickness of the protective layer is set to 25 μm, the thickness of the electrode layer is preferably 1.2 μm or less, more preferably 0.3 μm or less, particularly preferably 0.1 μm or less.

壓電膜12具有由第1電極層28及第2電極層30夾持壓電體層26，進而由第1保護層32及第2保護層34夾持該積層體之構成。這種壓電膜12在常溫下存在基於動態黏彈性測量而得之頻率1Hz中的損耗正切（Tanδ）成為0.1以上之極大值為較佳。藉此，即使壓電膜12從外部受到數Hz以下的比較緩慢且較大之彎曲變形，亦能夠將應變能有效地作為熱而擴散到外部，因此能夠防止在高分子基質與壓電體粒子的界面產生龜裂。 The piezoelectric film 12 has a structure in which the piezoelectric layer 26 is sandwiched between the first electrode layer 28 and the second electrode layer 30 , and the laminate is further sandwiched between the first protective layer 32 and the second protective layer 34 . Such a piezoelectric film 12 preferably has a maximum value of loss tangent (Tan δ ) at a frequency of 1 Hz obtained based on dynamic viscoelasticity measurement at normal temperature of 0.1 or more. Thereby, even if the piezoelectric film 12 receives a relatively slow and large bending deformation of several Hz or less from the outside, the strain energy can be effectively diffused to the outside as heat, so that the deformation between the polymer matrix and the piezoelectric particles can be prevented. interface cracks.

壓電膜12如下為較佳，亦即，基於動態黏彈性測量而得之頻率1Hz中的儲存彈性係數（E’）在0℃下為10～30GPa，在50℃下為1～10GPa。藉此，在常溫下壓電膜12在儲存彈性係數（E’）中能夠具有較大的頻率分散。亦即，能夠對於20Hz～20kHz的振動較硬地動作，對於數Hz以下的振動較柔軟地顯現。 The piezoelectric film 12 is preferably such that the storage elastic coefficient (E') at a frequency of 1 Hz based on dynamic viscoelasticity measurement is 10 to 30 GPa at 0°C and 1 to 10 GPa at 50°C. Thereby, the piezoelectric film 12 can have a large frequency dispersion in the storage elastic coefficient (E') at normal temperature. That is, it can operate relatively hard for vibrations of 20 Hz to 20 kHz, and can appear relatively soft for vibrations of several Hz or less.

又，壓電膜12為如下為較佳，亦即，厚度與基於動態黏彈性測量而得之頻率1Hz中的儲存彈性係數（E’）之積在0℃下為1.0×10 ⁶～2.0×10 ⁶N/m，在50℃下為1.0×10 ⁵～1.0×10 ⁶N/m。藉此，壓電膜12在不損害撓性及音響特性之範圍內能夠具備適當的剛性和機械強度。 In addition, it is preferable that the piezoelectric film 12 is such that the product of the thickness and the storage elastic coefficient (E') at a frequency of 1 Hz based on dynamic viscoelasticity measurement is 1.0×10 ⁶ to 2.0× 10 ⁶ N/m, 1.0×10 ⁵ to 1.0×10 ⁶ N/m at 50°C. Accordingly, the piezoelectric film 12 can have appropriate rigidity and mechanical strength within a range that does not impair flexibility and acoustic characteristics.

進而，壓電膜12為如下為較佳，亦即，從動態黏彈性測量所獲得之主曲線中，在25℃下頻率1kHz中之損耗正切（Tanδ）為0.05以上。Furthermore, the piezoelectric film 12 is preferably such that the loss tangent (Tan δ) at a frequency of 1 kHz at 25° C. is 0.05 or more in the main curve obtained from dynamic viscoelasticity measurement.

以下，參閱圖5～圖7，對壓電膜12的製造方法的一例進行說明。首先，準備在圖5中示意性地示出之第2保護層34的表面形成有第2電極層30之片狀物42b。進而，準備在圖7中示意性地示出之第1保護層32的表面形成有第1電極層28之片狀物42a。 Hereinafter, an example of a method for manufacturing the piezoelectric film 12 will be described with reference to FIGS. 5 to 7 . First, a sheet 42b in which the second electrode layer 30 is formed on the surface of the second protective layer 34 schematically shown in FIG. 5 is prepared. Furthermore, a sheet 42a in which the first electrode layer 28 is formed on the surface of the first protective layer 32 schematically shown in FIG. 7 is prepared.

片狀物42b可以藉由真空蒸鍍、濺鍍及電鍍等在第2保護層34的表面形成銅薄膜等作為第2電極層30來製作。同樣地，可以藉由真空蒸鍍、濺鍍、電鍍等在第1保護層32的表面上形成銅薄膜等作為第1電極層28來製作片狀物42a。或者，可以將在保護層上形成銅薄膜等之市售品片狀物用作片狀物42b和/或片狀物42a。片狀物42b及片狀物42a可以係相同者，亦可以係不同者。 The sheet 42 b can be produced by forming a copper thin film or the like on the surface of the second protective layer 34 as the second electrode layer 30 by vacuum evaporation, sputtering, electroplating, or the like. Similarly, the sheet 42a can be produced by forming a copper thin film or the like on the surface of the first protective layer 32 as the first electrode layer 28 by vacuum evaporation, sputtering, electroplating, or the like. Alternatively, a commercially available sheet in which a copper thin film or the like is formed on a protective layer may be used as the sheet 42b and/or the sheet 42a. The sheet 42b and the sheet 42a may be the same or different.

另外，關於保護層非常薄，且操作性差時等，依據需要可以使用帶隔板（臨時支撐體）之保護層。另外，作為隔板，能夠使用厚度為25～100μm的PET等。只要在電極層及保護層的熱壓接之後去除隔板即可。In addition, when the protective layer is very thin and the handleability is poor, a protective layer with a spacer (temporary support) can be used as needed. In addition, PET or the like having a thickness of 25 to 100 μm can be used as the separator. What is necessary is just to remove a separator after thermocompression bonding of an electrode layer and a protective layer.

接著，如圖6中示意性地表示那樣，在片狀物42b的第2電極層30上形成壓電體層26來製作積層了片狀物42b和壓電體層26之積層體46。Next, as schematically shown in FIG. 6 , the piezoelectric layer 26 is formed on the second electrode layer 30 of the sheet 42 b to manufacture a laminate 46 in which the sheet 42 b and the piezoelectric layer 26 are laminated.

只要依據壓電體層26之公知的方法形成壓電體層26即可。例如，在圖4中示出之高分子基質38中分散壓電體粒子40而成之壓電體層（高分子複合壓電體層）中，作為一例，以如下方式製作。首先，將上述氰乙基化PVA等高分子材料溶解於有機溶劑中，進而添加PZT粒子等壓電體粒子40，並進行攪拌來製備塗料。有機溶劑並無限制，能夠利用二甲基甲醯胺（DMF）、甲基乙基酮及環己酮等各種有機溶劑。在準備片狀物42b並製備了塗料之後，將該塗料澆鑄（塗佈）於片狀物42b上，蒸發並乾燥有機溶劑。藉此，如圖6所示那樣，製作在第2保護層34上具有第2電極層30且在第2電極層30上積層壓電體層26而成之積層體46。 The piezoelectric layer 26 may be formed by a known method for the piezoelectric layer 26 . For example, in the piezoelectric layer (polymer composite piezoelectric layer) in which piezoelectric particles 40 are dispersed in the polymer matrix 38 shown in FIG. 4 , it is fabricated as follows as an example. First, a polymer material such as cyanoethylated PVA is dissolved in an organic solvent, and piezoelectric particles 40 such as PZT particles are added and stirred to prepare a paint. The organic solvent is not limited, and various organic solvents such as dimethylformamide (DMF), methyl ethyl ketone, and cyclohexanone can be used. After the sheet 42b is prepared and the paint is prepared, the paint is cast (coated) on the sheet 42b, and the organic solvent is evaporated and dried. Thereby, as shown in FIG. 6 , a laminate 46 having the second electrode layer 30 on the second protective layer 34 and laminating the piezoelectric layer 26 on the second electrode layer 30 is manufactured.

塗料的澆鑄方法並無限制，能夠利用棒塗佈機、斜片式塗佈機（slidecoater）及塗層刀（doctorknife）等所有之公知的方法（塗佈裝置）。或者，若高分子材料為能夠加熱熔融之物質，則可以藉由加熱熔融高分子材料而製作向其中添加壓電體粒子40而成之熔融物，並藉由擠出成形等而在圖5中示出之片狀物42b上擠壓成薄片狀並進行冷卻，藉此製作如圖6所示之積層體46。 The casting method of the paint is not limited, and any known method (coating device), such as a bar coater, a slide coater, and a doctor knife, can be used. Alternatively, if the polymer material is a material that can be heated and melted, the polymer material can be heated and melted to produce a molten product in which piezoelectric particles 40 are added, and the molten material shown in FIG. 5 can be formed by extrusion molding or the like. The laminate 46 shown in FIG. 6 is produced by extruding the sheet-shaped object 42b shown in the sheet into a sheet shape and cooling it.

另外，如上所述，在壓電體層26中，除了在常溫下具有黏彈性之高分子材料以外亦可以向高分子基質38中添加PVDF等高分子壓電材料。向高分子基質38中添加該等高分子壓電材料時，只要溶解添加於上述塗料之高分子壓電材料即可。或者，只要向經加熱熔融之在常溫下具有黏彈性之高分子材料中添加需添加之高分子壓電材料來進行加熱熔融即可。 In addition, as described above, in the piezoelectric layer 26 , a polymer piezoelectric material such as PVDF may be added to the polymer matrix 38 in addition to the polymer material having viscoelasticity at room temperature. When adding these piezoelectric polymer materials to the polymer matrix 38, it is only necessary to dissolve the piezoelectric polymer materials added to the above-mentioned paint. Alternatively, it is sufficient to add the piezoelectric polymer material to be added to the viscoelastic polymer material that has been heated and melted at room temperature for heating and melting.

在形成壓電體層26之後，可以依據需要進行壓延處理。壓延處理可以進行1次，亦可以進行複數次。眾所周知，壓延處理係指藉由熱壓、加熱輥及一對加熱輥等來加熱被處理面的同時進行按壓以實施平坦化等之處理。 After the piezoelectric layer 26 is formed, a rolling treatment may be performed as necessary. The calendering treatment may be performed once or multiple times. As is well known, the calendering treatment refers to a treatment for flattening or the like by pressing while heating the surface to be treated with a hot press, a heating roll, a pair of heating rolls, and the like.

又，對在第2保護層34上具有第2電極層30，並且在第2電極層30上形成壓電體層26而成之積層體46的壓電體層26進行極化處理（polarization）。壓電體層26的極化處理的方法並無限制，能夠利用公知的方法。例如，例示出對進行極化處理之對象直接施加直流電場之電場極化處理。另外，在進行電場極化處理之情況下，可以在極化處理之前形成第1電極層28，並且利用第1電極層28及第2電極層30來進行電場極化處理。又，在製造壓電膜12時，極化處理不是向壓電體層26的面方向而是沿厚度方向進行極化為較佳。 In addition, the piezoelectric layer 26 of the laminate 46 having the second electrode layer 30 on the second protective layer 34 and the piezoelectric layer 26 formed on the second electrode layer 30 is subjected to polarization treatment (polarization). The method of polarization treatment of the piezoelectric layer 26 is not limited, and a known method can be used. For example, electric field polarization processing in which a DC electric field is directly applied to an object to be polarized is exemplified. In addition, when performing the electric field polarization treatment, the first electrode layer 28 may be formed before the polarization treatment, and the electric field polarization treatment may be performed using the first electrode layer 28 and the second electrode layer 30 . In addition, when the piezoelectric film 12 is manufactured, it is preferable to perform polarization treatment not in the surface direction of the piezoelectric layer 26 but in the thickness direction.

接著，如圖7中示意性地表示那樣，在積層體46的壓電體層26側，將之前準備之片狀物42a使第1電極層28朝向壓電體層26積層。進而，藉由第1保護層32及第2保護層34夾持該積層體，並且使用熱壓裝置及加熱輥等來進行熱壓接，以使積層體46與片狀物42a貼合。藉此，製作由設置於壓電體層26、壓電體層26的兩面之第1電極層28及第2電極層30以及形成於電極層的表面之第1保護層32及第2保護層34組成之壓電膜12。 Next, as schematically shown in FIG. 7 , the previously prepared sheet 42 a is laminated on the piezoelectric layer 26 side of the laminate 46 with the first electrode layer 28 facing the piezoelectric layer 26 . Furthermore, this laminated body is sandwiched between the first protective layer 32 and the second protective layer 34, and thermocompression bonding is performed using a heat press device, a heating roll, etc., so that the laminated body 46 and the sheet-like object 42a are bonded together. In this way, the piezoelectric body layer 26, the first electrode layer 28 and the second electrode layer 30 provided on both surfaces of the piezoelectric body layer 26, and the first protective layer 32 and the second protective layer 34 formed on the surface of the electrode layer were produced. The piezoelectric film 12.

藉由以這種方式製作之壓電膜12僅沿面方向而且沿厚度方向極化，並且即使在極化處理後不進行延伸處理亦可獲得較高的壓電特性。因此，壓電膜12在壓電特性中沒有面內各向異性，若施加驅動電壓，則在面方向的所有方向上，各向同性地伸縮。By making the piezoelectric film 12 in this way polarized not only in the plane direction but also in the thickness direction, high piezoelectric characteristics can be obtained even without stretching treatment after the polarization treatment. Therefore, the piezoelectric film 12 has no in-plane anisotropy in piezoelectric characteristics, and expands and contracts isotropically in all directions in the plane direction when a driving voltage is applied.

如上所述，壓電元件10係藉由折返壓電膜12而積層複數層，並且將積層並相鄰之壓電膜12彼此藉由黏貼層20而黏貼而成者。其中，如圖1所示那樣，本發明的壓電元件10在將壓電元件10的最厚部M的黏貼層的厚度設為t、將壓電元件10的最厚部M與棱線的最短距離設為L時，滿足“L≥50*t”。如上所述，棱線係指，壓電膜12的折返部的端部（外側端部）的頂部形成之折返線。另外，本發明中，壓電元件10的厚度係指，壓電膜12的積層方向的厚度。故，壓電元件10的最厚部M係指，壓電膜12的積層方向上的最厚的部分。又，如後所述，本發明中，壓電元件10的最厚部M係指，壓電元件10在壓電膜12的折返方向上的最厚的部分。 As described above, the piezoelectric element 10 is formed by laminating a plurality of layers by folding back the piezoelectric film 12 , and bonding the laminated and adjacent piezoelectric films 12 to each other with the adhesive layer 20 . Among them, as shown in FIG. 1, in the piezoelectric element 10 of the present invention, the thickness of the adhesive layer of the thickest part M of the piezoelectric element 10 is t, and the thickness of the thickest part M of the piezoelectric element 10 and the ridge line are When the shortest distance is set to L, "L≥50*t" is satisfied. As described above, the ridgeline refers to the folded line formed at the top of the end (outer end) of the folded portion of the piezoelectric film 12 . In addition, in the present invention, the thickness of the piezoelectric element 10 refers to the thickness in the stacking direction of the piezoelectric film 12 . Therefore, the thickest part M of the piezoelectric element 10 refers to the thickest part in the lamination direction of the piezoelectric film 12 . Also, as will be described later, in the present invention, the thickest portion M of the piezoelectric element 10 refers to the thickest portion of the piezoelectric element 10 in the folding direction of the piezoelectric film 12 .

本發明的壓電元件10藉由具有這種構成而在將壓電元件10黏貼於振動板時等，壓電元件10被按壓時，能夠防止壓電體層26及電極層在壓電膜12的折返部破損。其結果，本發明的壓電元件10例如作為激發器而使用於壓電揚聲器時，能夠適當地進行所設定之動作，並且適當地輸出目標音壓的聲音。Since the piezoelectric element 10 of the present invention has such a configuration, when the piezoelectric element 10 is pressed, such as when the piezoelectric element 10 is attached to a vibrating plate, it is possible to prevent the piezoelectric layer 26 and the electrode layer from being stuck on the piezoelectric film 12. The return part is damaged. As a result, when the piezoelectric element 10 of the present invention is used, for example, as an actuator in a piezoelectric speaker, it is possible to appropriately perform the set operation and output sound at a target sound pressure appropriately.

如上所述，作為一例，藉由折返壓電膜12而積層之壓電元件（積層壓電元件）用作使振動板振動而輸出聲音之激發器。將壓電元件用作激發器來製作壓電揚聲器之情況下，如後述之圖12中示意性地表示那樣，需要將壓電元件10黏貼於振動板62。壓電元件與振動板的黏貼例如經由黏著劑等黏貼劑來將壓電元件按壓到振動板來進行。又，依據需要加熱黏貼材料亦即壓電元件和/或振動板的同時進行該按壓。 As described above, as an example, a piezoelectric element (laminated piezoelectric element) laminated by folding back the piezoelectric film 12 is used as an exciter that vibrates a vibration plate to output sound. When producing a piezoelectric speaker using a piezoelectric element as an actuator, it is necessary to stick the piezoelectric element 10 to the diaphragm 62 as schematically shown in FIG. 12 to be described later. The bonding of the piezoelectric element and the vibration plate is performed, for example, by pressing the piezoelectric element to the vibration plate with an adhesive such as an adhesive. In addition, this pressing is performed while heating the adhesive material, that is, the piezoelectric element and/or the vibrating plate, as necessary.

其中，在折返壓電膜而積層之壓電元件中，在進行該按壓時對壓電膜施加表面壓力。若該表面壓力施加到折返部，則對壓電膜施加負擔，依據情況，存在導致電極層和/或壓電體層斷裂之問題。However, in the piezoelectric element in which the piezoelectric film is folded back and laminated, surface pressure is applied to the piezoelectric film during this pressing. When this surface pressure is applied to the folded portion, a burden is applied to the piezoelectric film, and there is a problem of causing breakage of the electrode layer and/or the piezoelectric layer in some cases.

又，如圖式例那樣，壓電體層26中使用了高分子複合壓電體之壓電膜12具有良好的撓性。因此，積層了該壓電膜12之壓電元件亦具有良好的撓性。故，在該情況下，使用能夠捲取之振動板並將壓電元件黏貼於該振動板作為激發器，藉此能夠實現能夠捲取之壓電揚聲器。然而，在該壓電揚聲器中，在捲取振動板時，同樣地，對壓電膜施加表面壓力，若該表面壓力施加到折返部，則依據情況導致電極層和/或壓電體層斷裂。 In addition, as in the example of the drawing, the piezoelectric film 12 in which a polymer composite piezoelectric body is used for the piezoelectric layer 26 has good flexibility. Therefore, the piezoelectric element in which the piezoelectric film 12 is laminated also has good flexibility. Therefore, in this case, a coilable piezoelectric speaker can be realized by using a coilable vibration plate and affixing a piezoelectric element to the vibration plate as an exciter. However, in this piezoelectric speaker, similarly, when the diaphragm is wound up, surface pressure is applied to the piezoelectric film, and when this surface pressure is applied to the folded portion, the electrode layer and/or the piezoelectric layer may be broken in some cases.

相對於此，關於本發明的壓電元件10，藉由折返壓電膜12而積層之（積層）壓電元件中，在將壓電元件10的最厚部M中的黏貼層20的厚度設為t、將壓電元件10的最厚部M與折返部的端部亦即棱線的最短距離設為L時，滿足“L≥50*t”。亦即，在本發明的壓電元件10中，最厚部M與棱線的最短距離為最厚部M的黏貼層20的厚度t的20倍以上，充分地分離。 On the other hand, in the piezoelectric element 10 of the present invention, in the piezoelectric element laminated (laminated) by folding the piezoelectric film 12 , the thickness of the adhesive layer 20 in the thickest part M of the piezoelectric element 10 is set to is t, and when L is the shortest distance between the thickest portion M of the piezoelectric element 10 and the end portion of the folded portion, that is, the ridge line, “L≧50*t” is satisfied. That is, in the piezoelectric element 10 of the present invention, the shortest distance between the thickest part M and the ridgeline is 20 times or more the thickness t of the adhesive layer 20 of the thickest part M, and they are sufficiently separated.

如上所述，在為了將壓電元件10黏貼於振動板來進行按壓時，在壓電元件10中施加最高的壓力的係最厚部M，對最厚部M的壓電膜12施加最高的表面壓力。同樣地，即使在捲取了振動板時，在壓電元件10中施加最高的壓力的亦係最厚部M，對最厚部M的壓電膜12施加最高的表面壓力。 As described above, when pressing to attach the piezoelectric element 10 to the vibrating plate, the thickest part M of the piezoelectric element 10 applies the highest pressure, and the highest pressure is applied to the piezoelectric film 12 of the thickest part M. surface pressure. Similarly, even when the diaphragm is wound up, the thickest part M is the part where the highest pressure is applied in the piezoelectric element 10, and the highest surface pressure is applied to the piezoelectric film 12 of the thickest part M.

其中，如上所述，本發明的壓電元件10中，最厚部M與棱線的最短距離L為最厚部的黏貼層20的厚度t的20倍以上。亦即，本發明的壓電元件10中，在將最厚部M設置於相對於折彎部的折返方向的內側而將壓電膜12受到最高的表面壓力之最厚部M與容易發生壓電體層26等的斷裂之壓電膜12的折返部充分地分離。因此，在本發明的壓電元件10中，壓電膜12的最厚部M受到最高的表面壓力，能夠防止對與最厚部M充分分離之折彎部的壓電膜12施加高的表面壓力。其結果，本發明的壓電元件10在向振動板按壓時等，能夠防止壓電體層26和/或電極層在折彎部發生斷裂。又，最厚部M為大致平面形狀，因此即使施加高的表面壓力，壓電體層26及電極層亦不會斷裂。故，本發明的壓電元件10即使藉由向振動板的黏貼等而被按壓之後，亦能夠適當地進行既定的動作。其結果，例如，將本發明的壓電元件10用作激發器之壓電揚聲器能夠適當地輸出所設定之音壓的聲音。 However, as described above, in the piezoelectric element 10 of the present invention, the shortest distance L between the thickest part M and the ridgeline is 20 times or more the thickness t of the adhesive layer 20 at the thickest part. That is, in the piezoelectric element 10 of the present invention, the thickest portion M and the thickest portion M where the piezoelectric film 12 receives the highest surface pressure are arranged on the inner side with respect to the folding direction of the bending portion. The folded portions of the piezoelectric film 12 where the electric layer 26 and the like are broken are sufficiently separated. Therefore, in the piezoelectric element 10 of the present invention, the thickest part M of the piezoelectric film 12 receives the highest surface pressure, and it is possible to prevent a high surface pressure from being applied to the piezoelectric film 12 of the bent part sufficiently separated from the thickest part M. pressure. As a result, the piezoelectric element 10 of the present invention can prevent the piezoelectric layer 26 and/or the electrode layer from being broken at the bent portion when the piezoelectric element 10 is pressed against the vibrating plate. Also, since the thickest portion M has a substantially planar shape, the piezoelectric layer 26 and the electrode layer will not be broken even if a high surface pressure is applied. Therefore, even after the piezoelectric element 10 of the present invention is pressed by sticking to the vibrating plate or the like, it can properly perform a predetermined operation. As a result, for example, a piezoelectric speaker using the piezoelectric element 10 of the present invention as an actuator can properly output sound at a set sound pressure.

在本發明的壓電元件10中，壓電元件10的最厚部M與棱線亦即折彎部的端部的最短距離L係指，壓電元件10的平面形狀中的最短距離。亦即，壓電元件10的最厚部M與棱線的最短距離L係指，從平面觀察壓電元件10之狀態的最短距離。如後所述，本發明中，壓電元件10的最厚部M係指，壓電膜12的折返方向亦即圖1中的橫向上的壓電元件10最厚的位置。其中，藉由將1張壓電膜折返2次以上而積層了3層以上的壓電膜12之壓電元件中，折返方向的兩端存在折返部。在該情況下，在壓電膜12的折返方向上，距最厚部M的近的一方的折返部成為最短距離L的對象。 In the piezoelectric element 10 of the present invention, the shortest distance L between the thickest portion M of the piezoelectric element 10 and the ridgeline, that is, the end of the bent portion refers to the shortest distance in the planar shape of the piezoelectric element 10 . That is, the shortest distance L between the thickest part M of the piezoelectric element 10 and the ridgeline means the shortest distance when viewing the state of the piezoelectric element 10 from a plane. As will be described later, in the present invention, the thickest part M of the piezoelectric element 10 refers to the thickest position of the piezoelectric element 10 in the direction of folding of the piezoelectric film 12 , that is, in the lateral direction in FIG. 1 . Among them, in a piezoelectric element in which three or more piezoelectric films 12 are stacked by folding one piezoelectric film twice or more, there are folded portions at both ends in the folded direction. In this case, in the folding direction of the piezoelectric film 12 , the closest folding portion to the thickest portion M is subject to the shortest distance L.

又，如圖1所示那樣，本發明的壓電元件10基本上以壓電膜12的棱線的位置在折返方向亦即平面形狀一致的方式折返壓電膜12而積層。然而，如圖8中示意性地表示的那樣，依據壓電元件10而在各折返部中，棱線的位置有可能在折返方向上不同。此時，不是將平面形狀亦即平面觀察時的距離遠的一方的棱線與最厚部M的距離L2，而是將平面形狀中的距離近的一方的棱線與最厚部M的距離L1作為壓電元件10中的最厚部M與棱線（折返端部）的最短距離L。 Also, as shown in FIG. 1 , the piezoelectric element 10 of the present invention is basically stacked by folding the piezoelectric film 12 so that the position of the ridge line of the piezoelectric film 12 is consistent in the folding direction, that is, the planar shape. However, as schematically shown in FIG. 8 , depending on the piezoelectric element 10 , the position of the ridgeline may differ in the folding direction in each of the folding portions. In this case, instead of the distance L2 between the ridge line on the far side and the thickest part M in plan view, that is, the distance L2 between the ridge line on the far side and the thickest part M, the distance between the ridge line on the short side in the plan shape and the thickest part M is calculated. L1 is the shortest distance L between the thickest part M and the ridgeline (turned-back end part) in the piezoelectric element 10 .

又，在圖1中，在最上層的黏貼層20表示最厚部M的厚度t，但藉由將1張壓電膜折返2次以上而積層了3層以上的壓電膜12之壓電元件中，黏貼層20存在複數層。例如，如圖1所示那樣，在將壓電膜12折返4次而積層了5層之情況下，黏貼層20存在4層。在該情況下，將各黏貼層20的最厚部M中的厚度的平均值作為壓電元件10的最厚部M中的黏貼層20的厚度t。例如，在圖1的情況下，將4個黏貼層20的各自的最厚部M中的黏貼層20的厚度的平均值作為壓電元件10的最厚部中的黏貼層20的厚度t。 In addition, in FIG. 1, the adhesive layer 20 on the uppermost layer shows the thickness t of the thickest part M, but the piezoelectricity of the piezoelectric film 12 stacked by three or more layers is obtained by folding one piezoelectric film twice or more. In the element, there are plural layers of the adhesive layer 20 . For example, as shown in FIG. 1 , when five layers are laminated by folding the piezoelectric film 12 four times, there are four adhesive layers 20 . In this case, the average value of the thicknesses in the thickest portion M of the respective adhesive layers 20 is defined as the thickness t of the adhesive layer 20 in the thickest portion M of the piezoelectric element 10 . For example, in the case of FIG. 1 , the average value of the thicknesses of the adhesive layers 20 in the thickest portions M of the four adhesive layers 20 is taken as the thickness t of the adhesive layer 20 in the thickest portion of the piezoelectric element 10 .

另外，關於本發明的壓電元件10中的最厚部M的確定方法及最厚部M中的黏貼層20的厚度t的確定方法，將在後面進行詳細敘述。又，在以下說明中，將壓電膜12的折返部的端部亦即棱線與壓電元件10的最厚部M的最短距離L已簡稱為“最短距離L”。進而，將最厚部M中的黏貼層20的厚度t亦簡稱為“黏貼層的厚度t”。 In addition, the method of determining the thickest part M in the piezoelectric element 10 of the present invention and the method of determining the thickness t of the adhesive layer 20 in the thickest part M will be described in detail later. In the following description, the shortest distance L between the ridgeline, which is the end of the folded portion of the piezoelectric film 12, and the thickest portion M of the piezoelectric element 10 is simply referred to as “the shortest distance L”. Furthermore, the thickness t of the adhesive layer 20 in the thickest portion M is also simply referred to as "thickness t of the adhesive layer".

如上所述，在本發明的壓電元件10中，最短距離L與黏貼層的厚度t滿足“L≥50*t”。最短距離L未達“50*t”時，壓電膜12的折返部與最厚部M太近，導致與表面壓力最高的最厚部M相等的表面壓力施加到折返部的壓電膜12。其結果，不能夠充分地防止折返部中的壓電體層26及電極層的斷裂。另外，基本上，壓電元件10的最厚部M越與壓電膜12的棱線分開，可越較佳地獲得本發明的效果。最短距離L滿足“L≥60*t”為較佳。另外，最短距離L的上限係壓電元件10的平面形狀中的壓電膜12的折返方向的長度的一半。 As described above, in the piezoelectric element 10 of the present invention, the shortest distance L and the thickness t of the adhesive layer satisfy “L≧50*t”. When the shortest distance L is less than "50*t", the folded portion of the piezoelectric film 12 is too close to the thickest portion M, and a surface pressure equal to the thickest portion M with the highest surface pressure is applied to the piezoelectric film 12 of the folded portion. . As a result, breakage of the piezoelectric layer 26 and the electrode layer in the folded portion cannot be sufficiently prevented. In addition, basically, the more the thickest part M of the piezoelectric element 10 is separated from the ridge line of the piezoelectric film 12, the better the effect of the present invention can be obtained. It is better that the shortest distance L satisfies "L≥60*t". In addition, the upper limit of the shortest distance L is half the length of the piezoelectric film 12 in the folding direction in the planar shape of the piezoelectric element 10 .

以下，參閱圖9，對壓電元件10中的最短距離L、最厚部及黏貼層的厚度t的確定方法進行說明。在以下說明中，為了方便，將基於壓電膜12的折返之折返部的端部中的折返線的方向亦即折返部中的壓電膜12的棱線的方向設為x方向。又，將棱線的方向亦即與x方向正交之方向亦即壓電元件10中的壓電膜12的折返方向作為y方向。 Hereinafter, referring to FIG. 9 , a method for determining the shortest distance L, the thickest portion, and the thickness t of the adhesive layer in the piezoelectric element 10 will be described. In the following description, for convenience, the direction of the folded line at the end of the folded portion based on the folded portion of the piezoelectric film 12 , that is, the direction of the ridgeline of the piezoelectric film 12 in the folded portion is referred to as the x direction. Also, let the direction of the ridge line, that is, the direction perpendicular to the x direction, that is, the direction in which the piezoelectric film 12 in the piezoelectric element 10 turns back, be the y direction.

在本發明中，如圖9的下段的俯視圖中示意性地表示那樣，壓電元件10的最短距離L、最厚部及黏貼層的厚度t由x方向的中心線亦即中心測量線x1、壓電元件10的x方向的長度亦即棱線的長度的僅5%、從x方向的端部位於內側之y方向的測量線x2及測量線x3、以及位於中心測量線x1與測量線x2的中間之y方向的測量線x4、及位於中心測量線x1與測量線x3的中間之y方向的測量線x5這5條線來進行測量，並確定。 In the present invention, as shown schematically in the plan view of the lower section of FIG. The length of the piezoelectric element 10 in the x direction is only 5% of the length of the ridgeline, the measurement line x2 and the measurement line x3 in the y direction located inside from the end in the x direction, and Five lines, the measurement line x4 in the y direction located between the central measurement line x1 and the measurement line x2, and the measurement line x5 in the y direction located between the central measurement line x1 and the measurement line x3 were measured and determined.

壓電元件10的最短距離L及最厚部M以如下方式確定。首先，在壓電元件10的中心測量線x1及測量線x2～x5的所有的測量線中，檢測壓電元件10的最高位置亦即最高點。接著，對於各測量線，測量最高點、與平面形狀中的棱線的最短距離。另外，在各折返部，棱線的位置在y方向上不同之情況下，該最短距離與上述圖8同樣地設為與距最高點最近的棱線的最短距離。接著，計算所測量之各測量線的最高點與棱線的最短距離的平均值。將該平均值作為壓電元件10中的最厚部M與棱線亦即折返部的端部的最短距離L。又，將從成為對象之棱線與y方向的最短距離L的位置中的x方向的整個區域設為壓電元件10中的最厚部M。亦即，在本發明的壓電元件10中，最厚部M係指，在y方向亦即壓電膜12的折返方向中，壓電元件10最厚的x方向的位置亦即棱線方向的位置。 The shortest distance L and the thickest part M of the piezoelectric element 10 are determined as follows. First, the highest position of the piezoelectric element 10 , that is, the highest point is detected on the central measurement line x1 of the piezoelectric element 10 and all the measurement lines x2 to x5 . Next, for each measurement line, the shortest distance between the highest point and the ridgeline in the planar shape is measured. In addition, when the positions of the ridgelines are different in the y direction in the respective turning portions, the shortest distance is the shortest distance from the ridgeline closest to the highest point, similarly to FIG. 8 described above. Next, the average value of the shortest distance between the highest point of each measured measurement line and the ridgeline is calculated. The average value is defined as the shortest distance L between the thickest portion M of the piezoelectric element 10 and the edge, that is, the end of the folded portion. Also, the entire region in the x direction from the position of the shortest distance L between the target ridgeline and the y direction is defined as the thickest portion M in the piezoelectric element 10 . That is, in the piezoelectric element 10 of the present invention, the thickest portion M refers to the position in the x direction, that is, the ridge line direction, where the piezoelectric element 10 is thickest in the y direction, that is, the folding direction of the piezoelectric film 12. s position.

壓電元件10的最高點的位置例如只要使用輪廓形狀測量儀測量壓電元件10的表面形狀來進行檢測即可。作為輪廓形狀測量儀，例如，例示出Mitutoyo Corporation製造之CV-3000。又，壓電元件10的最厚部M的厚度（後述之厚度T1）使用φ2mm的扁平型的探針，藉由數顯表來測量。關於最厚部M的厚度，亦對壓電元件10的中心測量線x1及測量線x2～x5這所有的線進行測量，將其平均值作為壓電元件10中的最厚部M的厚度。作為數顯表，例如，例示出Mitutoyo Corporation製造之ID-S112X。關於該測量，後述之壓電膜12的折返部中的壓電元件10的厚度（後述之厚度T2）亦相同。 The position of the highest point of the piezoelectric element 10 may be detected by, for example, measuring the surface shape of the piezoelectric element 10 using a contour measuring instrument. As a profile measuring instrument, for example, CV-3000 manufactured by Mitutoyo Corporation is exemplified. In addition, the thickness (thickness T1 described later) of the thickest part M of the piezoelectric element 10 was measured with a digital display meter using a flat probe of φ2 mm. The thickness of the thickest portion M is also measured for all of the central measurement line x1 and measurement lines x2 to x5 of the piezoelectric element 10 , and the average value thereof is taken as the thickness of the thickest portion M in the piezoelectric element 10 . As a digital display meter, for example, ID-S112X manufactured by Mitutoyo Corporation is exemplified. In this measurement, the same applies to the thickness of the piezoelectric element 10 in the folded portion of the piezoelectric film 12 described later (thickness T2 described later).

另一方面，最厚部M中的黏貼層的厚度t以如下方式確定。首先，對壓電元件10的所有的中心測量線x1及測量線x2～x5測量所確定之最厚部M中的黏貼層20的厚度。另外，關於各測量線中的最厚部M的黏貼層20的厚度，只要在各測量線的截面，用SEM（掃描式電子顯微鏡（Scanning Electron Microscope））觀察最厚部M，使用該SEM圖像，並且以公知的方法測量即可。厚度的測量在所有的黏貼層20的最厚部M進行。只要係圖1中示出之壓電元件10，則具有4層黏貼層20，因此對每1個截面在4個黏貼層20測量最厚部M中的黏貼層20的厚度。接著，計算所測量之所有的黏貼層20的最厚部M中的厚度的平均，將其平均值作為壓電元件10中的最厚部M的黏貼層20的厚度t。只要係圖1中示出之壓電元件10，則具有4層的黏貼層20。故，結合所有的中心測量線x1及測量線x2～x5的測量，“4層×5截面=20處”中的最厚部M的黏貼層20的厚度的平均值成為壓電元件10的黏貼層20的厚度t。 On the other hand, the thickness t of the adhesive layer in the thickest portion M is determined as follows. First, the thickness of the adhesive layer 20 in the identified thickest portion M is measured for all the central measurement lines x1 and measurement lines x2 to x5 of the piezoelectric element 10 . In addition, regarding the thickness of the adhesive layer 20 at the thickest part M in each measurement line, the thickness of the thickest part M is observed with an SEM (Scanning Electron Microscope) on the cross-section of each measurement line, and the SEM image is used. Like, and measured by known methods. The thickness measurement is performed at the thickest part M of all the adhesive layers 20 . As long as the piezoelectric element 10 shown in FIG. 1 has four adhesive layers 20 , the thickness of the adhesive layer 20 in the thickest part M is measured at the four adhesive layers 20 for each cross section. Next, the average of the measured thicknesses in the thickest portion M of all the adhesive layers 20 is calculated, and the average value is taken as the thickness t of the adhesive layer 20 in the thickest portion M of the piezoelectric element 10 . As long as it is the piezoelectric element 10 shown in FIG. 1 , it has four adhesive layers 20 . Therefore, combining the measurements of all the central measurement lines x1 and measurement lines x2 to x5, the average value of the thickness of the adhesive layer 20 of the thickest part M in "4 layers x 5 sections = 20 places" becomes the adhesive value of the piezoelectric element 10. The thickness t of layer 20 .

在本發明的壓電元件10中，最厚部M的厚度並無限制。其中，在本發明的壓電元件10中，將最厚部M的厚度設為T1、將壓電膜12的折返部中的壓電元件10的厚度設為T2時，厚度T1為厚度T2的115%以上為較佳。在以下說明中，為了方便將壓電膜12的折返部中的壓電元件10的厚度亦稱為“折返部的厚度”。換言之，在本發明的壓電元件10中，最厚部的厚度T1為折返部的厚度T2的1.15倍以上為較佳。藉由具有這種構成，從如下的觀點考慮為較佳：更佳地能夠防止按壓至振動板時及與振動板一起捲取時等的、壓電體層26和/或電極層在折返部的斷裂，並且抑制被按壓至振動板之後及與振動板一起捲取之後的ESR（Equivalent Series Resistance（等效串連電阻））的上升，從而能夠更穩定且有效地驅動等。最厚部的厚度T1為折返部的厚度T2的116%以上為更佳，117%以上為進一步較佳。 In the piezoelectric element 10 of the present invention, the thickness of the thickest portion M is not limited. Here, in the piezoelectric element 10 of the present invention, when the thickness of the thickest portion M is T1 and the thickness of the piezoelectric element 10 in the folded portion of the piezoelectric film 12 is T2, the thickness T1 is equal to the thickness T2. More than 115% is better. In the following description, the thickness of the piezoelectric element 10 in the folded portion of the piezoelectric film 12 is also referred to as “thickness of the folded portion” for convenience. In other words, in the piezoelectric element 10 of the present invention, the thickness T1 of the thickest portion is preferably 1.15 times or more the thickness T2 of the folded portion. By having such a configuration, it is preferable from the viewpoint that it is possible to more preferably prevent the piezoelectric layer 26 and/or the electrode layer from being bent at the folded portion when being pressed to the vibration plate or when being wound up with the vibration plate. Break, and suppress the increase of ESR (Equivalent Series Resistance (equivalent series resistance)) after being pressed to the vibration plate and after being wound up with the vibration plate, so that it can be driven more stably and efficiently. The thickness T1 of the thickest part is more preferably 116% or more of the thickness T2 of the folded part, and more preferably 117% or more.

又，最厚部的厚度T1為折返部的厚度T2的130%以下為較佳。若最厚部的厚度T1相對於折返部的厚度T2太厚，則難以黏貼到振動板等、壓電元件10向面方向的伸縮變得不穩定，在使用了能夠捲取之振動板時，可能產生在進行了捲取時在振動板產生凹凸（發生反射）等不便。相對於此，藉由將最厚部的厚度T1設為上述範圍內，能夠較佳地避免發生該等不便。 Also, the thickness T1 of the thickest portion is preferably 130% or less of the thickness T2 of the folded portion. If the thickness T1 of the thickest part is too thick compared to the thickness T2 of the folded part, it will be difficult to adhere to the vibration plate, etc., and the expansion and contraction of the piezoelectric element 10 in the plane direction will become unstable. When a coilable vibration plate is used, Inconveniences such as unevenness (reflection) may occur on the vibrating plate when winding is performed. On the other hand, by making the thickness T1 of the thickest part into the said range, these inconveniences can be preferably avoided.

另外，折返部的厚度係以包括從壓電元件10中的最上方（積層方向的端部）的折返的彎曲部端部至沿折返方向的內側的1mm為止的部分之方式，使用φ2mm的扁平型的探針，藉由數顯表來測量壓電元件10的厚度，將最厚的厚度設為壓電元件10中的折返部的厚度T2。In addition, the thickness of the folded portion is to include a portion from the end of the folded bent portion at the top (end in the lamination direction) of the piezoelectric element 10 to 1 mm inside in the folded direction, and a flat surface of φ2 mm is used. type probe, the thickness of the piezoelectric element 10 is measured by a digital display meter, and the thickest thickness is set as the thickness T2 of the folded portion in the piezoelectric element 10 .

另外，在本發明中，最厚部的厚度T1及折返部的厚度T2，如上所述，均在圖9中示出之壓電元件10的中心測量線x1及測量線x2～x5中，測量最厚部及折返部的厚度，將其平均值設為壓電元件10中的最厚部的厚度T1及折返部的厚度T2。In addition, in the present invention, the thickness T1 of the thickest portion and the thickness T2 of the folded portion are all measured on the central measurement line x1 and the measurement lines x2 to x5 of the piezoelectric element 10 shown in FIG. 9 as described above. The average values of the thicknesses of the thickest portion and the folded portion are the thickness T1 of the thickest portion and the thickness T2 of the folded portion in the piezoelectric element 10 .

以下，參閱圖10的概念圖，對壓電元件10的製造方法的一例進行說明。如上所述，壓電元件10係藉由折返壓電膜12而積層，並且將積層並相鄰之壓電膜12藉由黏貼層20而黏貼者。如圖10的第1段及第2段所示那樣，在壓電膜12的一方端部附近設置黏貼層20，接著，如第3段所示那樣，藉由折返壓電膜12而積層。關於第1段、第2段…，將在圖中，從上方表示段數。如第4段所示那樣，藉由折返而積層之壓電膜12，並藉由將能夠按壓棱線方向的整個區域之輥50沿折返方向進行移動而按壓並黏貼積層了2層的壓電膜12。輥50可以使用輥對。又，依據需要，作為輥50而可以使用加熱輥並且進行加熱，同時進行壓電膜12的黏貼。進而，如第5段所示那樣，在所積層之壓電膜12上設置黏貼層20，如第6段所示那樣，再次折返壓電膜12而積層。接著，如第7段所示那樣，藉由使能夠按壓棱線方向的整個區域之輥50向折返方向移動而黏貼所積層之壓電膜12。依據壓電膜12的積層數來重複該操作，從而能夠製作積層了所希望的層數的壓電膜12之壓電元件。 Hereinafter, an example of a method of manufacturing the piezoelectric element 10 will be described with reference to the conceptual diagram of FIG. 10 . As described above, the piezoelectric element 10 is laminated by folding the piezoelectric film 12 , and the laminated and adjacent piezoelectric film 12 is bonded by the adhesive layer 20 . As shown in the first and second paragraphs of FIG. 10 , the adhesive layer 20 is provided near one end of the piezoelectric film 12 , and then, as shown in the third paragraph, the piezoelectric film 12 is folded back to form a laminate. Regarding the first stage, the second stage..., the number of stages will be shown from above in the drawing. As shown in the fourth paragraph, the piezoelectric film 12 stacked by folding is pressed and pasted by pressing and pasting the piezoelectric film 12 laminated in two layers by moving the roller 50 capable of pressing the entire area in the ridge direction in the folding direction. film12. As the roller 50, a pair of rollers can be used. In addition, if necessary, a heating roller may be used as the roller 50 and the piezoelectric film 12 may be attached while heating. Furthermore, as shown in the fifth paragraph, an adhesive layer 20 is provided on the laminated piezoelectric film 12, and as shown in the sixth paragraph, the piezoelectric film 12 is folded back again to be laminated. Next, as shown in the seventh paragraph, the laminated piezoelectric film 12 is pasted by moving the roller 50 capable of pressing the entire area in the ridge line direction in the return direction. By repeating this operation depending on the number of piezoelectric films 12 to be laminated, a piezoelectric element in which a desired number of piezoelectric films 12 are laminated can be manufactured.

如圖1等所示那樣，在本發明的壓電元件10中，壓電膜12的厚度基本在整個面上均勻（大致均勻）。故，壓電元件的厚度及最厚部M的位置以及厚度以黏貼層20的厚度進行控制。如圖10中示出之壓電元件的製造方法中，在輥50的移動方向上部分地調節用於黏貼所積層之壓電膜12之輥50的按壓力。亦即，藉由減弱輥50的按壓力來加厚其位置的黏貼層20，其結果，能夠加厚壓電元件。藉此，在所製造之壓電元件10中，能夠在壓電膜12的折返方向（圖9中的y方向）的任意位置設置最厚部M。另外，在製造壓電元件10時，可以對所有的黏貼層20進行輥50的按壓力的變更，或者，亦可以將不變更輥50的按壓力之黏貼層20設定為1層或複數層。 As shown in FIG. 1 and the like, in the piezoelectric element 10 of the present invention, the thickness of the piezoelectric film 12 is substantially uniform (approximately uniform) over the entire surface. Therefore, the thickness of the piezoelectric element and the position and thickness of the thickest portion M are controlled by the thickness of the adhesive layer 20 . In the manufacturing method of the piezoelectric element as shown in FIG. 10 , the pressing force of the roller 50 for pasting the laminated piezoelectric film 12 is partially adjusted in the moving direction of the roller 50 . That is, by weakening the pressing force of the roller 50, the adhesive layer 20 at its position is thickened, and as a result, the piezoelectric element can be thickened. Thereby, in the manufactured piezoelectric element 10 , the thickest portion M can be provided at any position in the folding direction (y direction in FIG. 9 ) of the piezoelectric film 12 . In addition, when manufacturing the piezoelectric element 10, the pressing force of the roller 50 may be changed for all the adhesive layers 20, or the adhesive layer 20 that does not change the pressing force of the roller 50 may be set to one layer or a plurality of layers.

本發明的壓電元件10藉由對第1電極層28及第2電極層30施加驅動電壓而伸縮壓電體層26。因此，需要將第1電極層28及第2電極層30和外部電源等外部裝置進行電連接。第1電極層28及第2電極層30與外部裝置連接之方法能夠利用公知的各種方法。 In the piezoelectric element 10 of the present invention, the piezoelectric layer 26 expands and contracts by applying a driving voltage to the first electrode layer 28 and the second electrode layer 30 . Therefore, it is necessary to electrically connect the first electrode layer 28 and the second electrode layer 30 to an external device such as an external power source. Various well-known methods can be used for connecting the first electrode layer 28 and the second electrode layer 30 to external devices.

作為一例，如圖11中示意性地表示那樣，在一方的端部延長壓電膜12，設置從積層有壓電膜12之區域突出之突出部12a。另外，例示出在該突出部12a設置用於與外部裝置電連接之引線之方法。另外，在本發明中，突出部具體地表示，對於平面形狀而言，亦即成為從積層方向觀察時，不與其他壓電膜12重複之單層的區域。又，在圖11中，省略壓電元件10的最厚部。 As an example, as schematically shown in FIG. 11 , the piezoelectric film 12 is extended at one end, and a protruding portion 12 a protruding from the region where the piezoelectric film 12 is laminated is provided. Moreover, the method of providing the lead wire for electrically connecting with an external device to this protrusion part 12a is shown as an example. In addition, in the present invention, the protruding portion specifically refers to a single-layer region that does not overlap with other piezoelectric films 12 in terms of planar shape, that is, when viewed from the lamination direction. In addition, in FIG. 11 , the thickest part of the piezoelectric element 10 is omitted.

如圖11所示那樣，在為壓電元件10的突出部12a連接有用於與電源裝置等外部裝置電連接之第1引線72及第2引線74。第1引線72係從第1電極層28進行電性引出之配線，第2引線74係從第2電極層30進行電性引出之配線。在以下說明中，在不需要區別第1引線72和第2引線74之情況下，亦簡稱為引線。 As shown in FIG. 11 , a first lead 72 and a second lead 74 for electrically connecting to an external device such as a power supply device are connected to the protruding portion 12 a of the piezoelectric element 10 . The first lead 72 is a wiring electrically drawn out from the first electrode layer 28 , and the second lead 74 is a wiring electrically drawn out from the second electrode layer 30 . In the following description, when there is no need to distinguish the first lead 72 and the second lead 74, they are also simply referred to as leads.

在本發明的壓電元件10中，電極層與引線的連接方法亦即引出方法並無限制，能夠利用各種方法。作為一例，例示出如下方法：在保護層上形成貫通孔，為了填充貫通孔而設置由銀膠等金屬膏形成之電極連接構件，在該電極連接構件中設置引線。作為其他方法，例示出在電極層與壓電體層之間或者在電極層與保護層之間設置棒狀或片狀的引出用電極，將引線連接至該引出用電極之方法。或者，可以將引線直接***到電極層與壓電體層之間或者電極層與保護層之間，將引線連接到電極層。作為其他方法，例示出如下方法：使保護層及電極層的一部分從壓電體層沿面方向突出，將引線連接到突出的電極層。另外，引線與電極層的連接藉由使用銀膠等金屬膏之方法、使用焊料之方法、使用導電性的接著劑之方法等公知的方法來進行即可。作為較佳的電極引出方法，例示出日本特開2014-209724號公報中所記載之方法及日本特開2016-015354號公報中所記載之方法等。 In the piezoelectric element 10 of the present invention, the connection method of the electrode layer and the lead wire, that is, the drawing method is not limited, and various methods can be used. As an example, a method of forming a through hole in the protective layer, providing an electrode connection member made of metal paste such as silver glue to fill the through hole, and providing a lead wire in the electrode connection member is exemplified. As another method, a method of providing a rod-shaped or sheet-shaped lead-out electrode between the electrode layer and the piezoelectric layer or between the electrode layer and the protective layer, and connecting a lead wire to the lead-out electrode is exemplified. Alternatively, a lead wire may be directly inserted between the electrode layer and the piezoelectric body layer or between the electrode layer and the protective layer, and the lead wire may be connected to the electrode layer. As another method, a method is exemplified in which a part of the protective layer and the electrode layer protrudes from the piezoelectric layer in the direction along the plane, and a lead wire is connected to the protruded electrode layer. In addition, the connection between the lead wire and the electrode layer may be performed by a known method such as a method using a metal paste such as silver paste, a method using solder, or a method using a conductive adhesive. As a preferable electrode extraction method, the method described in Unexamined-Japanese-Patent No. 2014-209724, the method described in Unexamined-Japanese-Patent No. 2016-015354, etc. are illustrated.

又，在壓電元件10中，並不延長壓電膜12的端部，如國際公開第2020/095812號的圖18中示出那樣，在壓電膜12的棱線的方向亦即與折返方向正交之方向上設置如從壓電膜突出之出島那樣的突出部，在此處可以設置用於連接外部裝置之引出配線。進而，在本發明的壓電元件中，可以依據需要併用複數個該等突出部。 In addition, in the piezoelectric element 10, the end of the piezoelectric film 12 is not extended, and as shown in FIG. Protrusions such as islands protruding from the piezoelectric film are provided in the direction perpendicular to the direction, and lead-out wiring for connecting to external devices can be provided here. Furthermore, in the piezoelectric element of the present invention, a plurality of these protrusions may be used in combination as necessary.

如後所述，本發明的壓電元件10能夠利用於各種用途中。其中，本發明的壓電元件10作為藉由使振動板振動而輸出聲音之激發器而被較佳地利用。As will be described later, the piezoelectric element 10 of the present invention can be used in various applications. Among them, the piezoelectric element 10 of the present invention is preferably used as an exciter that outputs sound by vibrating a diaphragm.

圖12中示意性地表示本發明的壓電揚聲器的一例。本發明的壓電揚聲器係藉由將本發明的壓電元件10黏貼於振動板來用作使振動板振動而輸出聲音之激發器者。如圖12所示那樣，壓電揚聲器60係藉由黏貼層68而將壓電元件10黏貼於振動板62者。另外，在本發明的壓電揚聲器中，黏貼於1張振動板62之壓電元件的數量並不限制為1個，可以將複數個壓電元件10黏貼於1張振動板62。又，例如，可以藉由將2個壓電元件10設置於1張振動板62並對各壓電元件10施加不同的驅動電壓而以1張振動板62輸出例如立體聲。 An example of the piezoelectric speaker of the present invention is schematically shown in FIG. 12 . The piezoelectric speaker of the present invention is used as an exciter that vibrates the diaphragm to output sound by affixing the piezoelectric element 10 of the present invention to the diaphragm. As shown in FIG. 12 , in the piezoelectric speaker 60 , the piezoelectric element 10 is adhered to the vibrating plate 62 through the adhesive layer 68 . In addition, in the piezoelectric speaker of the present invention, the number of piezoelectric elements attached to one diaphragm 62 is not limited to one, and a plurality of piezoelectric elements 10 may be attached to one diaphragm 62 . Also, for example, by providing two piezoelectric elements 10 on one vibration plate 62 and applying different driving voltages to the respective piezoelectric elements 10 , for example, stereo sound can be output from one vibration plate 62 .

在本發明的壓電揚聲器60中，振動板62並無限制，只要係作為藉由基於激發器的振動而輸出聲音之振動板發揮作用者，則能夠利用各種片狀物。In the piezoelectric speaker 60 of the present invention, the diaphragm 62 is not limited, and various sheet-shaped objects can be used as long as it functions as a diaphragm that outputs sound by vibration of the exciter.

在本發明的壓電揚聲器60中，作為振動板62，作為一例，例示出由聚對酞酸乙二酯（PET）、聚丙烯（PP）、聚苯乙烯（PS）、聚碳酸酯（PC）、聚苯硫醚（PPS）、聚甲基丙烯酸甲酯（PMMA）、聚醚醯亞胺（PEI）、聚醯亞胺（PI）、聚萘二甲酸乙二酯（PEN）、三乙醯纖維素（TAC）及環狀烯烴系樹脂等組成之樹脂薄膜、由發泡聚苯乙烯、發泡苯乙烯及發泡聚乙烯等組成之發泡塑膠片、以及將波浪狀的紙板的單面或兩面黏貼在其他紙板而成之各種瓦楞紙材料等。又，本發明的壓電揚聲器60亦能夠較佳地利用有機電致發光（OLED（Organic Light Emitting Diode））顯示器、液晶顯示器、微型LED（Light Emitting Diode：發光二極體）顯示器及無機電致發光顯示器等各種顯示元件等來作為振動板62。進而，本發明的壓電揚聲器60亦能夠較佳地利用智慧型手機、行動電話、平板終端、膝上型電腦等個人電腦及智慧型手錶等隨身器件等電子元件來作為振動板62。除此之外，本發明的壓電揚聲器亦能夠較佳地利用不鏽鋼、鋁、銅及鎳等由各種金屬以及各種合金等組成之薄膜金屬來作為振動板62。由於包括振動板62係顯示元件及電子元件等情況，因此振動板62可以係具有撓性者。如上所述，壓電膜12具有良好的撓性。因此，積層了壓電膜12之本發明的積層壓電元件10亦具有良好的撓性。故，藉由使用具有撓性之振動板62，能夠實現能夠彎曲、折彎、折疊及捲取等之壓電揚聲器。 In the piezoelectric speaker 60 of the present invention, as the diaphragm 62, polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polycarbonate (PC ), polyphenylene sulfide (PPS), polymethyl methacrylate (PMMA), polyetherimide (PEI), polyimide (PI), polyethylene naphthalate (PEN), triethylene Resin films composed of acyl cellulose (TAC) and cyclic olefin resins, foamed plastic sheets composed of expanded polystyrene, expanded styrene and expanded polyethylene, and sheets of corrugated cardboard A variety of corrugated paper materials made of one or both sides pasted on other cardboard. In addition, the piezoelectric speaker 60 of the present invention can also preferably utilize organic electroluminescent (OLED (Organic Light Emitting Diode)) displays, liquid crystal displays, micro LED (Light Emitting Diode: Light Emitting Diode) displays and inorganic electroluminescence. Various display elements such as a light-emitting display are used as the vibration plate 62 . Furthermore, the piezoelectric speaker 60 of the present invention can also preferably use electronic components such as personal computers such as smart phones, mobile phones, tablet terminals, and laptops, and portable devices such as smart watches as the vibration plate 62 . In addition, the piezoelectric speaker of the present invention can preferably use thin film metals composed of various metals and alloys such as stainless steel, aluminum, copper, and nickel as the vibration plate 62 . Since the vibrating plate 62 may be a display element or an electronic element, the vibrating plate 62 may be flexible. As described above, the piezoelectric film 12 has good flexibility. Therefore, the multilayer piezoelectric element 10 of the present invention in which the piezoelectric film 12 is laminated also has good flexibility. Therefore, by using the flexible diaphragm 62, it is possible to realize a piezoelectric speaker capable of bending, bending, folding, winding, and the like.

在本發明的壓電揚聲器60中，將振動板62與壓電元件10進行黏貼之黏貼層68並無限制，只要係能夠將振動板62與壓電元件10（壓電膜12）進行黏貼，則能夠利用各種黏貼劑。在本發明的壓電揚聲器60中，將振動板62與壓電元件10進行黏貼之黏貼層68能夠利用各種與將上述相鄰之壓電膜12進行黏貼之黏貼層20相同者。又，較佳的黏貼層68亦相同。 In the piezoelectric speaker 60 of the present invention, the adhesive layer 68 for bonding the vibrating plate 62 and the piezoelectric element 10 is not limited, as long as the vibrating plate 62 and the piezoelectric element 10 (piezoelectric film 12) can be bonded, Various adhesives can be used. In the piezoelectric speaker 60 of the present invention, the adhesive layer 68 for adhering the diaphragm 62 and the piezoelectric element 10 can use any of the same adhesive layers 20 as the adhesive layer 20 for adhering the above-mentioned adjacent piezoelectric films 12 . Also, the preferred adhesive layer 68 is also the same.

在本發明的壓電揚聲器60中，黏貼層68的厚度並無限制，只要依據黏貼層68的形成材料而適當地設定能夠顯現充分的黏貼力之厚度即可。其中，在本發明的壓電揚聲器60中，黏貼層68薄者能夠提高壓電膜12的伸縮能量（振動能量）的傳遞效果並提高能量效率。又，若黏貼層厚且剛性高，則有可能會限制壓電元件10的伸縮。若考慮到這一點，關於將振動板62與壓電元件10進行黏貼之黏貼層68的厚度，黏貼後的厚度為10～1000μm為較佳，30～500μm為更佳，50～300μm為進一步較佳。 In the piezoelectric speaker 60 of the present invention, the thickness of the adhesive layer 68 is not limited, as long as the thickness can be appropriately set to exhibit sufficient adhesive force according to the forming material of the adhesive layer 68 . Among them, in the piezoelectric speaker 60 of the present invention, the thinner the adhesive layer 68 can improve the transmission effect of the stretching energy (vibration energy) of the piezoelectric film 12 and improve the energy efficiency. In addition, if the adhesive layer is thick and rigid, expansion and contraction of the piezoelectric element 10 may be limited. Taking this point into consideration, the thickness of the adhesive layer 68 for bonding the vibrating plate 62 and the piezoelectric element 10 is preferably 10 to 1000 μm, more preferably 30 to 500 μm, and still more preferably 50 to 300 μm. good.

如上所述，在本發明的壓電元件10中，壓電膜12係由第1電極層28及第2電極層30夾持壓電體層26而成者。壓電體層26係在高分子基質38中分散壓電體粒子40而成者為較佳。 As described above, in the piezoelectric element 10 of the present invention, the piezoelectric film 12 is formed by sandwiching the piezoelectric layer 26 between the first electrode layer 28 and the second electrode layer 30 . The piezoelectric layer 26 is preferably formed by dispersing piezoelectric particles 40 in the polymer matrix 38 .

若對具有這種壓電體層26之壓電膜12的第2電極層30及第1電極層28施加電壓，則依據所施加之電壓而壓電體粒子40向極化方向伸縮。其結果，壓電膜12（壓電體層26）向厚度方向收縮。同時，由於帕松比的關係，壓電膜12亦沿面方向伸縮。該伸縮為0.01～0.1%左右。如上所述，壓電體層26的厚度較佳為8～300μm左右。故，厚度方向的伸縮最大亦只是0.3μm左右為非常小。相對於此，壓電膜12亦即壓電體層26在面方向上具有明顯大於厚度之尺寸。故，例如，若壓電膜12的長邊為20cm，則藉由施加電壓，壓電膜12最大伸縮0.2mm左右。 When a voltage is applied to the second electrode layer 30 and the first electrode layer 28 of the piezoelectric film 12 having the piezoelectric layer 26 , the piezoelectric particles 40 expand and contract in the polarization direction according to the applied voltage. As a result, the piezoelectric film 12 (piezoelectric layer 26 ) shrinks in the thickness direction. At the same time, due to the relationship of Poisson's ratio, the piezoelectric film 12 also expands and contracts along the surface direction. This expansion and contraction is about 0.01 to 0.1%. As described above, the thickness of the piezoelectric layer 26 is preferably about 8 to 300 μm. Therefore, the maximum expansion and contraction in the thickness direction is only about 0.3 μm, which is very small. In contrast, the piezoelectric film 12 , that is, the piezoelectric layer 26 has a dimension significantly larger than its thickness in the plane direction. Therefore, for example, if the long side of the piezoelectric film 12 is 20 cm, the piezoelectric film 12 expands and contracts by a maximum of about 0.2 mm by applying a voltage.

如上所述，壓電元件10係藉由折返而積層了5層壓電膜12而成者。又，壓電元件10藉由黏貼層68而黏貼於振動板62。藉由壓電膜12的伸縮而壓電元件10亦沿相同方向伸縮。藉由該壓電元件10的伸縮，振動板62彎曲，其結果，向厚度方向振動。藉由該厚度方向的振動，振動板62發出聲音。亦即，振動板62依據施加於壓電膜12之電壓（驅動電壓）的大小來進行振動，並依據施加於壓電膜12之驅動電壓來發出聲音。 As described above, the piezoelectric element 10 is formed by stacking five piezoelectric films 12 by folding back. In addition, the piezoelectric element 10 is adhered to the vibrating plate 62 via the adhesive layer 68 . As the piezoelectric film 12 expands and contracts, the piezoelectric element 10 also expands and contracts in the same direction. Due to the expansion and contraction of the piezoelectric element 10, the vibrating plate 62 bends, and as a result, vibrates in the thickness direction. The vibrating plate 62 emits sound by the vibration in the thickness direction. That is, the vibrating plate 62 vibrates according to the magnitude of the voltage (driving voltage) applied to the piezoelectric film 12 , and emits sound according to the driving voltage applied to the piezoelectric film 12 .

其中，已知由PVDF等高分子材料組成之通常之壓電膜藉由在極化處理後沿單軸方向進行延伸處理來對延伸方向配向分子鏈並作為結果在延伸方向上可獲得較大的壓電特性。因此，通常之壓電膜的壓電特性具有面內各向異性，施加了電壓時的面方向的伸縮量有各向異性。相對於此，在壓電元件10中，在圖4中示出之由高分子基質38中分散壓電體粒子40而成之高分子複合壓電體組成之壓電膜12即使在極化處理後不進行延伸處理亦可獲得較強的壓電特性，因此壓電特性中不具有面內各向異性，並在面方向上向所有方向各向同性地伸縮。亦即，在圖式例的壓電元件10中，構成壓電元件10之圖4中示出之壓電膜12二維上各向同性地伸縮。依據在二維上各向同性地伸縮之這種積層了壓電膜12之壓電元件10，與積層了僅向一個方向大幅度伸縮之PVDF等通常的壓電膜之情況相比，能夠以較大的力振動振動板62，並能夠發出更大且優美之聲音。 Among them, it is known that a general piezoelectric film composed of a polymer material such as PVDF aligns molecular chains in the direction of extension by performing an extension process in a uniaxial direction after polarization treatment, and as a result, a large piezoelectric film can be obtained in the direction of extension. Piezoelectric properties. Therefore, the piezoelectric properties of a general piezoelectric film have in-plane anisotropy, and the amount of expansion and contraction in the plane direction when a voltage is applied has anisotropy. In contrast, in the piezoelectric element 10, the piezoelectric film 12 composed of a polymer composite piezoelectric body in which piezoelectric particles 40 are dispersed in a polymer matrix 38 shown in FIG. Strong piezoelectric properties can be obtained without post-stretching treatment, so the piezoelectric properties do not have in-plane anisotropy, and expand and contract isotropically in all directions in the plane direction. That is, in the piezoelectric element 10 of the illustrated example, the piezoelectric film 12 shown in FIG. 4 constituting the piezoelectric element 10 expands and contracts isotropically in two dimensions. According to the piezoelectric element 10 laminated with the piezoelectric film 12 that expands and contracts isotropically in two dimensions, compared with the case of laminating a general piezoelectric film such as PVDF that expands and contracts greatly in only one direction, it can be The vibrating plate 62 is vibrated with a greater force, and a louder and more beautiful sound can be produced.

如上所述，圖式例的壓電元件10係積層了5層這樣的壓電膜12而成者。圖式例的壓電元件10進一步用黏貼層20將相鄰之壓電膜12彼此黏貼。因此，即使每1片的壓電膜12的剛性低且拉伸力小，但藉由積層壓電膜12，剛性變高，作為壓電元件10的拉伸力亦變大。其結果，壓電元件10即使為振動板62具有一定程度的剛性者，亦以較大的力使振動板62充分地彎曲並使振動板62充分地向厚度方向振動，能夠使振動板62發出聲音。又，壓電體層26越厚，壓電膜12的拉伸力變得越大，但是使其伸縮相同量所需之驅動電壓相應地變大。其中，如上所述，在壓電元件10中，較佳的壓電體層26的厚度最大亦只有300μm左右，因此施加於各個壓電膜12之電壓小亦能夠充分地伸縮壓電膜12。 As described above, the piezoelectric element 10 of the illustrated example is formed by laminating five such piezoelectric films 12 . The piezoelectric element 10 of the example shown in the figure further adheres the adjacent piezoelectric films 12 to each other with an adhesive layer 20 . Therefore, even if the piezoelectric film 12 per sheet has low rigidity and a small tensile force, by laminating the piezoelectric film 12, the rigidity becomes high, and the tensile force as the piezoelectric element 10 also increases. As a result, even if the vibration plate 62 of the piezoelectric element 10 has a certain degree of rigidity, the vibration plate 62 can be sufficiently bent with a relatively large force to sufficiently vibrate the vibration plate 62 in the thickness direction, and the vibration plate 62 can be emitted. sound. Also, the thicker the piezoelectric layer 26 is, the larger the tensile force of the piezoelectric film 12 becomes, but the driving voltage required to expand and contract the piezoelectric film 12 by the same amount increases accordingly. Among them, as mentioned above, in the piezoelectric element 10 , the thickness of the piezoelectric layer 26 is preferably only about 300 μm at the maximum, so the piezoelectric film 12 can be stretched and stretched sufficiently even with a small voltage applied to each piezoelectric film 12 .

這種本發明的壓電元件除了如上所述的壓電揚聲器以外，例如能夠較佳地利用於各種感測器、音響元件、觸覺介面、超音波換能器、致動器、減振材料（阻尼器）及振動發電裝置等各種用途中。具體而言，作為使用本發明的壓電元件之感測器，例示出聲波感測器、超音波感測器、壓力感測器、觸覺感測器、應變感測器及振動感測器等。使用本發明的壓電膜及積層壓電元件之感測器尤其在裂縫檢測等基礎結構的檢測及異物混入檢測等製造現場中的檢查中有用。作為使用本發明的壓電元件之音響元件，除了如上所述的壓電揚聲器（激發器）以外，例示出擴音器、拾音器以及公知的各種揚聲器及激發器等。作為使用本發明的壓電元件之音響元件的具體用途，例示出使用於車、電列車、飛機及設備人等之雜訊消除器、人造聲帶、用於防止害蟲·有害動物侵入之蜂鳴器以及具有聲音輸出功能之家具、壁紙、照片、頭盔、護目鏡、頭靠、標牌及設備人等。作為使用本發明的壓電元件之觸覺介面的應用例，例示出汽車、智慧型手機、智慧型手錶及遊戲機等。作為使用本發明的壓電元件之超音波換能器，例示出超音波探頭及水中受波器等。作為使用本發明的壓電元件之致動器的用途，例示出防止水滴附著、輸送、攪拌、分散及研磨等。作為使用本發明的壓電元件之減振材料的應用例，例示出容器、載具、建築物以及滑雪板及球拍等運動器材等。進而，作為使用本發明的壓電元件之振動發電裝置的應用例，例示出道路、地板、床墊、椅子、鞋子、輪胎、車輪及電腦鍵盤等。 This piezoelectric element of the present invention can be preferably used in various sensors, acoustic components, tactile interfaces, ultrasonic transducers, actuators, vibration-damping materials ( Dampers) and vibration power generation devices and other applications. Specifically, as a sensor using the piezoelectric element of the present invention, an acoustic wave sensor, an ultrasonic wave sensor, a pressure sensor, a touch sensor, a strain sensor, a vibration sensor, etc. are exemplified. . The sensor using the piezoelectric film and the laminated piezoelectric element of the present invention is particularly useful in inspections at manufacturing sites such as inspections of infrastructure such as crack inspections and inspections of foreign matter incorporation. As an acoustic element using the piezoelectric element of the present invention, in addition to the piezoelectric speaker (exciter) described above, a speaker, a pickup, and various known speakers and exciters are exemplified. Specific applications of the acoustic element using the piezoelectric element of the present invention include noise cancellers used in cars, trains, airplanes, equipment, etc., artificial vocal cords, and buzzers for preventing the invasion of pests and harmful animals. And furniture, wallpapers, photos, helmets, goggles, headrests, signs and equipment with sound output functions. Examples of application of the tactile interface using the piezoelectric element of the present invention include automobiles, smart phones, smart watches, game machines, and the like. Examples of the ultrasonic transducer using the piezoelectric element of the present invention include an ultrasonic probe, an underwater wave receiver, and the like. Examples of applications of the actuator using the piezoelectric element of the present invention include prevention of water droplet adhesion, transportation, stirring, dispersion, and grinding. Examples of applications of vibration-damping materials using the piezoelectric element of the present invention include containers, vehicles, buildings, and sports equipment such as skis and rackets. Furthermore, as application examples of the vibration power generating device using the piezoelectric element of the present invention, roads, floors, mattresses, chairs, shoes, tires, wheels, computer keyboards, and the like are exemplified.

以上，對本發明的壓電元件及壓電揚聲器進行了詳細說明，但本發明並不限定於上述例，在不脫離本發明的宗旨之範圍內，可以進行各種改進或變更，這是理所當然的。 [實施例] As mentioned above, the piezoelectric element and the piezoelectric speaker of the present invention have been described in detail, but the present invention is not limited to the above examples, and various improvements and changes can be made without departing from the gist of the present invention, of course. [Example]

以下，舉出本發明的具體的實施例，對本發明進行更詳細地說明。Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention.

[壓電膜的製作] 藉由圖5～圖7中示出之方法來製作了如圖4中示出之壓電膜。首先，以下述組成比將氰乙基化PVA（CR-V Shin-Etsu Chemical Co.,Ltd.製造）溶解於二甲基甲醯胺（DMF）。然後，在該溶液中，以下述組成比添加PZT粒子作為壓電體粒子，用螺旋槳混合器（轉速2000rpm）攪拌，以製備用於形成壓電體層之塗料。 ·PZT粒子···········300質量份 ·氰乙基化PVA·······30質量份 ·DMF··············70質量份另外，PZT粒子使用了以相對於Pb=1莫耳成為Zr=0.52莫耳、Ti=0.48莫耳之方式，用球磨機在800℃下將成為主成分之Pb氧化物、Zr氧化物及Ti氧化物的粉末進行濕式混合而成之混合粉末鍛燒5小時之後進行粉碎處理者。 [Production of Piezoelectric Film] The piezoelectric film as shown in FIG. 4 was produced by the method shown in FIGS. 5 to 7 . First, cyanoethylated PVA (manufactured by CR-V Shin-Etsu Chemical Co., Ltd.) was dissolved in dimethylformamide (DMF) at the following composition ratio. Then, to this solution, PZT particles were added as piezoelectric particles at the following composition ratio, and stirred with a propeller mixer (rotational speed: 2000 rpm) to prepare a coating material for forming a piezoelectric layer. ・PZT particles 300 parts by mass ·Cyanoethylated PVA...30 parts by mass ·DMF··················· 70 parts by mass In addition, PZT particles are used so that Zr=0.52 mole and Ti=0.48 mole relative to Pb=1 mole, and Pb oxide, Zr oxide, and Ti, which are the main components, are oxidized at 800°C with a ball mill. The mixed powder obtained by wet mixing the powder of the product is calcined for 5 hours and then pulverized.

另一方面，準備了2張在厚度為4μm的PET薄膜上真空蒸鍍厚度為20nm的銅薄膜而成之片狀物。亦即，在本例中，第1電極層及第2電極層係厚度為20nm的銅蒸鍍薄膜，第1保護層及第2保護層成為厚度為4μm的PET薄膜。在1張片狀物的銅薄膜（第2電極層）上，使用斜片式塗佈機，塗佈了用於形成預先製備之壓電體層之塗料。接著，藉由在120℃的加熱板上加熱並乾燥在片狀物上塗佈了塗料之物質而使DMF蒸發。藉此，在PET製第2保護層上具有銅製第2電極層，在其上製作了具有厚度為50μm的壓電體層（高分子複合壓電體層）之積層體。 On the other hand, two sheets in which a copper thin film with a thickness of 20 nm was vacuum-deposited on a PET film with a thickness of 4 μm were prepared. That is, in this example, the first electrode layer and the second electrode layer are deposited copper films with a thickness of 20 nm, and the first protective layer and the second protective layer are PET films with a thickness of 4 μm. On the copper thin film (second electrode layer) of one sheet, the paint for forming the piezoelectric body layer prepared in advance was applied using a slant die coater. Next, the DMF was evaporated by heating and drying the sheet-coated material on a hot plate at 120°C. In this way, a laminate having a piezoelectric layer (polymer composite piezoelectric layer) having a thickness of 50 μm was formed on a second protective layer made of PET with a second electrode layer made of copper.

對所製作之壓電體層（積層體），使用加熱輥對實施了壓延處理。加熱輥對的溫度設為100℃。在進行了壓延處理之後，將所製作之壓電體層沿厚度方向進行了極化處理。 The produced piezoelectric layer (laminated body) was rolled using a pair of heating rollers. The temperature of the heating roller pair was set to 100°C. After the rolling treatment, the fabricated piezoelectric layer was subjected to polarization treatment in the thickness direction.

將另一張片狀物積層於積層體，以使銅薄膜（第1電極層）朝向壓電體層。接著，使用加熱輥對，將積層體與片狀物的積層體以120℃的溫度進行熱壓接，從而接著壓電體層與第1電極層而製作了如圖4所示之壓電膜。 Laminate another sheet on the laminate so that the copper thin film (first electrode layer) faces the piezoelectric layer. Next, the laminated body and sheet-shaped laminated body were thermocompression-bonded at a temperature of 120° C. using a heating roller pair, and the piezoelectric layer and the first electrode layer were bonded to form a piezoelectric film as shown in FIG. 4 .

[實施例1] 將所製作之壓電膜切割成20×25cm的矩形。如圖10所示那樣，沿25cm的方向以5cm間隔重複進行設置黏貼層、折返壓電膜並用輥按壓來黏貼該壓電膜。藉此，製作了藉由黏貼積層5層壓電膜並相鄰地積層之壓電膜而成之平面形狀為20×5cm的如圖2中示出之壓電元件。故，壓電元件成為長度為20cm的邊成為棱線（折返線）。黏貼層使用熱塑性樹脂。輥使用長度為20cm以上者，以按壓棱線方向的整個區域之方式，沿折返方向移動的同時進行了壓電膜的按壓及黏貼。輥加熱至熱塑性樹脂熔融之溫度以上。另外，基於輥的按壓在中途稍微減弱了一部分按壓力。減弱按壓力的位置在所有的層設為相同的位置。 [Example 1] The fabricated piezoelectric film was cut into a rectangle of 20×25 cm. As shown in FIG. 10 , the piezoelectric film was repeatedly attached at intervals of 5 cm in the direction of 25 cm by placing the adhesive layer, folding back the piezoelectric film, and pressing it with a roller. Thereby, a piezoelectric element having a planar shape of 20×5 cm as shown in FIG. 2 was produced by laminating five piezoelectric films and adjacently stacking the piezoelectric films. Therefore, the side of the piezoelectric element with a length of 20 cm becomes a ridge line (return line). A thermoplastic resin is used for the adhesive layer. Using a roller with a length of 20 cm or more, the piezoelectric film was pressed and pasted while moving in the turn-back direction so as to press the entire area in the ridge direction. The rollers are heated above the temperature at which the thermoplastic resin melts. Also, the roller-based pressing slightly weakens a part of the pressing force halfway through. The position where the pressing force is reduced is set to the same position for all layers.

[實施例2及比較例1] 在積層壓電元件時，除了變更基於輥的按壓力及減弱按壓力的位置以外，以與實施例1相同的方式製作了壓電元件。 [Example 2 and Comparative Example 1] When laminating the piezoelectric element, the piezoelectric element was produced in the same manner as in Example 1, except that the pressing force by the roller and the position for reducing the pressing force were changed.

[最短距離L及最厚部的確定] 在所製作之壓電元件中，如圖9所示那樣，分別地在棱線方向上，在棱線方向的中心設定中心測量線x1、在從端部向內側1cm的位置設定測量線x2及測量線x3、在中心測量線x1與測量線x2的中間設定測量線x4、在中心測量線x1與測量線x3的中間設定測量線x5。在各測量線中，使用輪廓形狀測量儀（Mitutoyo Corporation製造、CV-3000）測量表面形狀，檢測了最高點的位置。對於各測量線測量最高點與壓電元件的棱線的最短距離，並求出了其平均值。將該平均值設為壓電元件中的棱線與最厚部的最短距離L。又，將沿折返方向從棱線僅分離最短距離L之棱線方向的位置設為壓電元件中的最厚部。將結果示於下述表中。 [Determination of the shortest distance L and the thickest part] In the produced piezoelectric element, as shown in Fig. 9, in the ridge direction, the center measurement line x1 is set at the center of the ridge direction, the measurement line x2 is set at a position 1 cm inward from the end, and The measurement line x3, the measurement line x4 is set in the middle of the central measurement line x1 and the measurement line x2, and the measurement line x5 is set in the middle of the central measurement line x1 and the measurement line x3. In each measurement line, the surface shape was measured using a contour shape measuring instrument (manufactured by Mitutoyo Corporation, CV-3000), and the position of the highest point was detected. The shortest distance between the highest point and the ridgeline of the piezoelectric element was measured for each measurement line, and the average value thereof was obtained. This average value was defined as the shortest distance L between the ridge line and the thickest part in the piezoelectric element. Also, the position in the ridgeline direction separated from the ridgeline by the shortest distance L in the folding direction is defined as the thickest part of the piezoelectric element. The results are shown in the following tables.

[最厚部及折返部的厚度的測量] 在所製作之壓電元件中，測量了所確定之最厚部的厚度T1及折返部的厚度T2。另外，折返部的厚度係、壓電膜的兩端的黏貼層的端部的位置中的壓電元件的兩個表面的積層方向上的間隔。另外，關於最厚部及折返部的厚度的測量，均在所設定之中心測量線x1及測量線x2～x5下進行，將其平均值設為最厚部的厚度T1及折返部的厚度T2 A. 最厚部及折返部的厚度的測量使用φ2mm的扁平型探針，藉由數顯表（Mitutoyo Corporation製造、ID-S112X）來進行。將結果示於下述表中。 [Measurement of the thickness of the thickest part and the folded part] In the produced piezoelectric element, the thickness T1 of the determined thickest part and the thickness T2 of the folded part were measured. In addition, the thickness of the folded portion refers to the distance between the two surfaces of the piezoelectric element in the stacking direction at the positions of the ends of the adhesive layer at both ends of the piezoelectric film. In addition, the measurement of the thickness of the thickest part and the folded part is carried out under the set central measurement line x1 and the measured lines x2~x5, and the average value thereof is set as the thickness T1 of the thickest part and the thickness T2 of the folded part A. The thickness of the thickest part and the folded part is measured using a φ2mm flat probe with a digital display (manufactured by Mitutoyo Corporation, ID-S112X). The results are shown in the following tables.

[黏貼層的厚度t的測量] 在所設定之中心測量線x1及測量線x2～x5切割所製作之壓電元件，用SEM觀察了所確定之最厚部的截面。從SEM圖像中，測量了各截面中的最厚部的各黏貼層的厚度。將所有的最厚部的黏貼層的厚度進行平均而設為壓電元件中的最厚部中的黏貼層的厚度t。在本例中，黏貼層為4層、測量線為5條，因此黏貼層的厚度t係20處的黏貼層的厚度的平均值。將結果示於下述表中。另外，在進行了後述之評價之後測量了黏貼層的厚度t。 [Measurement of the thickness t of the adhesive layer] The manufactured piezoelectric element was cut along the set central measurement line x1 and measurement lines x2 to x5, and the cross-section of the determined thickest part was observed by SEM. From the SEM image, the thickness of each adhesive layer at the thickest part in each section was measured. The thickness t of the adhesive layer in the thickest portion of the piezoelectric element was obtained by averaging the thicknesses of all the adhesive layers in the thickest portion. In this example, there are 4 layers of adhesive layers and 5 measuring lines, so the thickness t of the adhesive layer is the average value of the thicknesses of the adhesive layers at 20 locations. The results are shown in the following tables. In addition, the thickness t of the adhesive layer was measured after performing the evaluation described later.

[評價] ＜斷裂部的檢測＞在溫度為23℃、相對濕度為40%的環境下，使用按壓版對所製作之壓電元件的平面形狀的整個面施加了10分鐘1.5Mpa的壓力。然後，藉由光學顯微鏡來觀察壓電元件中的壓電膜的折返部，檢測是否存在壓電體層及電極層中的斷裂部。將未確認到斷裂部之情況評價為A、將確認到斷裂部之情況評價為B。 [evaluate] ＜Detection of broken part＞ In an environment with a temperature of 23° C. and a relative humidity of 40%, a pressure of 1.5 MPa was applied for 10 minutes to the entire planar surface of the fabricated piezoelectric element using a press plate. Then, the folded portion of the piezoelectric film in the piezoelectric element was observed with an optical microscope to detect the presence or absence of fractured portions in the piezoelectric layer and the electrode layer. The case where a fractured portion was not confirmed was rated as A, and the case where a fractured portion was confirmed was rated as B.

＜ESR的測量＞在進行了上述按壓之後，關於壓電元件，使用Agilent Technologies, Inc.製造之阻抗分析儀4294A，測量了測量頻率10kHz下的ESR（等價串聯電阻）。將結果示於下述表中。＜Measurement of ESR＞ After the above pressing, regarding the piezoelectric element, ESR (equivalent series resistance) at a measurement frequency of 10 kHz was measured using an impedance analyzer 4294A manufactured by Agilent Technologies, Inc. The results are shown in the following tables.

[表1] 最短距離 L [μm] 黏貼層的厚度 t [μm] 最厚部的厚度 T1 [μm] 折返部的厚度 T2 [μm] 50*t [μm] T1/T2 的比率 [%] 評價斷裂部的檢測 ESR [Ω] 實施例1 3000 30 420 360 1500 117 A 1.03 實施例2 2500 38 410 380 1900 108 A 1.12 比較例1 1500 35 420 380 1750 111 B 1.51 最短距離L係指，壓電元件的最厚部與棱線的最短距離黏貼層的厚度t係指，壓電元件的最厚部的黏貼層的厚度 [Table 1] Shortest distance L [μm] Thickness of adhesive layer t [μm] Thickness T1 of the thickest part [μm] Thickness T2 of the folded part [μm] 50*t [μm] T1/T2 ratio [%] evaluate Detection of Fractures ESR [Ω] Example 1 3000 30 420 360 1500 117 A 1.03 Example 2 2500 38 410 380 1900 108 A 1.12 Comparative example 1 1500 35 420 380 1750 111 B 1.51 The shortest distance L refers to the shortest distance between the thickest part of the piezoelectric element and the ridgeline. The thickness of the adhesive layer t refers to the thickness of the adhesive layer at the thickest part of the piezoelectric element.

如表中示出那樣，在藉由折返壓電膜而積層並由黏貼層黏貼相鄰之壓電膜之壓電元件中，關於棱線（折返部的端部）與壓電元件的最厚部的最短距離L為最厚部中的黏貼層的厚度t的50倍以上（L≥50*t）的本發明的壓電元件，即使在對平面形狀的整個面施加壓力，在折返部亦不產生壓電體層及電極層的斷裂。故，本發明的壓電元件即使為了構成壓電揚聲器而按壓/黏貼於振動板時，在折返部的壓電體層及電極層亦不發生斷裂，能夠輸出目標音壓的聲音。又，最厚部的厚度T1相對於折返部的厚度T2在較佳的範圍內的115%以上實施例1與不滿足該條件之實施例2相比，按壓後的ESR低。故，實施例1的壓電元件在為了構成壓電揚聲器而按壓/黏貼於振動板之後，能夠更穩定且有效地驅動。相對於此，最短距離L未達黏貼層的厚度t的50倍之比較例1的壓電元件在平面形狀的整個面被施加壓力時，認為折返部的壓電膜受到較強的表面壓力而在折返部發生壓電體層及電極層的斷裂。因此，該壓電元件為了構成壓電揚聲器而按壓/黏貼於振動板時，在折返部的壓電體層及電極層發生斷裂，有可能無法輸出目標音壓的聲音。又，與本發明產品相比，比較例1的壓電元件的按壓後的ESR高。因此，比較例1的壓電元件在為了構成壓電揚聲器而按壓/黏貼於振動板之後，存在驅動不穩定，又，效率亦變差之可能性。藉由以上結果，本發明的效果明顯。 [產業上之可利用性] As shown in the table, in the piezoelectric element laminated by folding back the piezoelectric film and pasting the adjacent piezoelectric film with the adhesive layer, the maximum thickness of the ridge line (the end of the folded part) and the piezoelectric element In the piezoelectric element of the present invention, the shortest distance L of the portion is 50 times or more than the thickness t of the adhesive layer in the thickest portion (L≥50*t), even if pressure is applied to the entire surface of the planar shape, the piezoelectric element at the folded portion is also Breakage of the piezoelectric layer and the electrode layer does not occur. Therefore, even when the piezoelectric element of the present invention is pressed/attached to the diaphragm to form a piezoelectric speaker, the piezoelectric layer and the electrode layer at the folded portion are not broken, and sound at a target sound pressure can be output. In addition, the ESR after pressing was lower in Example 1, in which the thickness T1 of the thickest portion was at least 115% of the thickness T2 of the folded portion, compared to Example 2, which did not satisfy this condition. Therefore, the piezoelectric element of Example 1 can be driven more stably and efficiently after being pressed/attached to the vibration plate to form a piezoelectric speaker. On the other hand, when the piezoelectric element of Comparative Example 1 in which the shortest distance L is less than 50 times the thickness t of the adhesive layer is applied to the entire surface of the planar shape, it is considered that the piezoelectric film at the folded portion is subjected to a strong surface pressure. Breakage of the piezoelectric layer and the electrode layer occurs at the folded portion. Therefore, when the piezoelectric element is pressed/attached to the diaphragm to form a piezoelectric speaker, the piezoelectric layer and the electrode layer at the folded portion may be broken, and sound at a target sound pressure may not be output. Also, the piezoelectric element of Comparative Example 1 had a higher ESR after pressing than the product of the present invention. Therefore, after the piezoelectric element of Comparative Example 1 is pressed/attached to the vibrating plate to form a piezoelectric speaker, the driving may be unstable and the efficiency may also be deteriorated. From the above results, the effect of the present invention is obvious. [Industrial availability]

作為壓電揚聲器等，能夠較佳地利用於各種用途中。It can be suitably utilized in various applications as a piezoelectric speaker and the like.

10:壓電元件 12:壓電膜 20,68:黏貼層 26:壓電體層 28:第1電極層 30:第2電極層 32:第1保護層 34:第2保護層 38:高分子基質 40:壓電體粒子 42a,42b:片狀物 46:積層體 50:輥 60:壓電揚聲器 62:振動板 72:第1引線 74:第2引線 M:最厚部 10: Piezoelectric element 12: Piezoelectric film 20,68: Paste layer 26: Piezoelectric layer 28: The first electrode layer 30: The second electrode layer 32: 1st protective layer 34: The second protective layer 38: polymer matrix 40: Piezoelectric particles 42a, 42b: flakes 46: laminated body 50: roll 60: Piezoelectric speaker 62: Vibration plate 72: 1st lead 74: 2nd lead M: the thickest part

圖1係示意性地表示本發明的壓電元件的一例之圖。圖2係用於說明本發明的壓電元件的一例之示意圖。圖3係用於說明本發明的壓電元件的另一例之示意圖。圖4係示意性地表示本發明的壓電元件中所使用之壓電膜的一例之圖。圖5係用於說明壓電膜的製作方法的一例之示意圖。圖6係用於說明壓電膜的製作方法的一例之示意圖。圖7係用於說明壓電膜的製作方法的一例之示意圖。圖8係用於說明本發明的壓電元件之示意圖。圖9係用於說明本發明的壓電元件的一例之示意圖。圖10係用於說明本發明的壓電元件的製造方法的一例之示意圖。圖11係示意性地表示本發明的壓電元件的另一例之圖。圖12係示意性地表示本發明的壓電揚聲器的一例之圖。 FIG. 1 is a diagram schematically showing an example of the piezoelectric element of the present invention. Fig. 2 is a schematic diagram illustrating an example of the piezoelectric element of the present invention. Fig. 3 is a schematic diagram illustrating another example of the piezoelectric element of the present invention. FIG. 4 is a diagram schematically showing an example of a piezoelectric film used in the piezoelectric element of the present invention. FIG. 5 is a schematic diagram for explaining an example of a method for producing a piezoelectric film. FIG. 6 is a schematic diagram for explaining an example of a method for producing a piezoelectric film. FIG. 7 is a schematic diagram for explaining an example of a method of manufacturing a piezoelectric film. Fig. 8 is a schematic diagram for explaining the piezoelectric element of the present invention. Fig. 9 is a schematic diagram illustrating an example of the piezoelectric element of the present invention. Fig. 10 is a schematic diagram for explaining an example of a method for manufacturing a piezoelectric element of the present invention. Fig. 11 is a diagram schematically showing another example of the piezoelectric element of the present invention. Fig. 12 is a diagram schematically showing an example of the piezoelectric speaker of the present invention.

10:壓電元件 10: Piezoelectric element

12:壓電膜 12: Piezoelectric film

20:黏貼層 20: Paste layer

26:壓電體層 26: Piezoelectric layer

28:第1電極層 28: The first electrode layer

30:第2電極層 30: The second electrode layer

32:第1保護層 32: 1st protective layer

34:第2保護層 34: The second protective layer

L:最短距離 L: the shortest distance

M:最厚部 M: the thickest part

t:厚度 t: thickness

T1,T2:厚度 T1, T2: Thickness

Claims

一種壓電元件，其藉由折返具有撓性之壓電膜而積層了複數層所述壓電膜，其特徵在於，所述壓電元件具有將積層並相鄰之所述壓電膜進行黏貼之黏貼層，在將所述壓電元件的最厚部的所述黏貼層的厚度設為t、將所述壓電膜的折返部的端部與所述壓電元件的最厚部的最短距離設為L時，滿足L≥50*t。 A piezoelectric element in which a plurality of layers of the piezoelectric film are laminated by folding back a flexible piezoelectric film, characterized in that, The piezoelectric element has an adhesive layer for adhering the laminated and adjacent piezoelectric films, When the thickness of the adhesive layer at the thickest part of the piezoelectric element is t, and the shortest distance between the end of the folded part of the piezoelectric film and the thickest part of the piezoelectric element is L , satisfy L≥50*t.

如請求項1所述的壓電元件，其從所述壓電膜的積層方向觀察時為矩形，所述矩形的長邊與所述壓電膜的折返線一致。 The piezoelectric element according to claim 1, which is rectangular when viewed from the stacking direction of the piezoelectric film, The long side of the rectangle coincides with the return line of the piezoelectric film.

如請求項1所述的壓電元件，其中所述最厚部的厚度為所述壓電膜的折返部的厚度的115%以上。 The piezoelectric element as claimed in claim 1, wherein The thickness of the thickest portion is 115% or more of the thickness of the folded portion of the piezoelectric film.

如請求項1所述的壓電元件，其中所述壓電膜具有壓電體層、設置於所述壓電體層的兩面之電極層及設置成覆蓋所述電極層之保護層。 The piezoelectric element as claimed in claim 1, wherein The piezoelectric film has a piezoelectric layer, electrode layers provided on both surfaces of the piezoelectric layer, and a protective layer provided to cover the electrode layers.

如請求項4所述的壓電元件，其中所述壓電體層是在高分子材料中具有壓電體粒子之高分子複合壓電體。 The piezoelectric element as claimed in claim 4, wherein The piezoelectric layer is a polymer composite piezoelectric body having piezoelectric particles in a polymer material.

如請求項5所述的壓電元件，其中所述高分子材料具有氰乙基。 The piezoelectric element as claimed in item 5, wherein The polymer material has cyanoethyl groups.

如請求項6所述的壓電元件，其中所述高分子材料是氰乙基化聚乙烯醇。 The piezoelectric element as claimed in claim 6, wherein The polymer material is cyanoethylated polyvinyl alcohol.

一種壓電揚聲器，其藉由將請求項1至請求項7中任一項所述的壓電元件黏貼於振動板而成。A piezoelectric speaker, which is formed by pasting the piezoelectric element described in any one of claim 1 to claim 7 on a vibration plate.