201008304 六、發明說明： 【發明所屬之技術領域】 本發明係關於駐極體材料，且特別關於一駐極體揚聲 器與其製造方法。 【先前技術】 一靜電揚聲器依照庫倫定律（coulomb's law)，同時具有 相異或同性之電荷的兩個導體可產生推或挽力（push or 籲 pull force)。交變的推挽靜電力可導致具靜電荷振動板 (diaphragm)的振動，且因此產生聲音。一靜電揚聲器一般 包括兩個多孔導電板或電極板與一介於導電板或電極板之 間且由其所驅動的振動板。氣隙（aiT gap)可將電極與振動板 隔開以提供振動板振動之空間。振動板通常薄且輕，且因 此使靜電揚聲器之暫態反應(transition response)、於高頻之 延伸性（expansion capabiiity)、聲音流暢度（sm〇〇也ness 〇f sound)、聲音逼真度（acoustic fidelity)與低失真度 (distortion) ’優於其他形式之揚聲器，例如電動（dynamic)、 動圈(mwingcoil)式或壓電(piez〇electric)式揚聲器。此外， 振動板必須具備靜電荷，以當訊號傳至電極板時，在藉由 電極板所形成電場的作用下，允許誘導靜電力驅動振動板。 由於結構簡單’靜電揚聲器可被製造成多種尺寸以適 應日增之對於小且薄之電子裝置的需要。然而-般靜電揚 聲選用一直流對直流電源轉換器（DC_DC e〇nverter)以提 供由導體所構成振動板上的靜電荷。考慮到直流對直流電 源轉換器之尺寸、成本與電源消耗，已發展駐極體材料來 201008304 取代直流對直流電源轉換器。駐極體為一具有一準永久電 猗或偶極極化的介電材料。一駐極體產生内部及外部電 碭，其可為一永磁的靜電等效，請參閱G. M. SesslerK 198〇 在 Topics in Applied Physics vol. 33 第一章第！頁所載及美 國專利第4,288,584號(Mishra)。駐極體電荷可包括淨電荷 (例如表面及/或空間電荷）及/或偶極極化。淨電荷包括捕捉 及負電荷載體層。 一示範之駐極體揚聲器顯示於第i圖中，其可包括多 •孔電極板6a與6b及一駐極體振動板4。電極6a與6b可具 有一些開口 61a與61b且於各電極板上至少具有3〇%開孔 率。電極板6a與6b可由金屬或覆蓋導電薄骐之塑膠材料 形成。開口 61a與61b可提供允許聲波通過。駐極體振動 板4可包括一導電層2，其被失於駐極體層1&與lb之間。 駐極體層la與lb可包括正電荷或負電荷或經定位後於駐 極體振動板4的垂直方向具有相對偶極極化。藉由支持構 件5a與5b可維持電極板6a與6b及駐極體振動板4在適 籲當的地方。可由絕緣材料製造支持構件5a舆分。藉由絕 緣兀件51a、51b、5.2a與52b可將電極板6a、6b與駐極體 振動板分開。在一駐極體揚聲器之操作中，各訊號源乃與 7b分別經由導線8&與8b輸出一交替訊號至電極板仏舆 6b。訊號導致在電極板6&與6b及駐極體層u與比間發 展一時變電場(time-Varying eleciric fieId)，而於電極板 與6b及駐極體振動板4之間產生一靜電力。靜電力可導致 駐極體振動板4振動而產生聲音。所產生之聲波可通·過孔 洞61a與61b ’因此，聲波可於駐極體揚聲器外被收聽。 201008304 然而’為了使駐極體揚聲器增強其聲音逼真度 (acoustic fidelity)與低失真度（i〇w distortion)，其需要一具 有極佳之駐極體特性的駐極體材料輿需要小心處理的製程 以製造一薄的駐極體-金屬-駐極體結構。已知可由不同聚 合物製作駐極體。藉由一直流電暈處理，於聚合物駐極體 薄膜中產生電荷。上述不同的聚合物包括含氟聚合物，例 如聚四氟乙烯（poly-tetrafluoroethylene, PTFE)與氟化乙丙 烯(fluorinated ethylene propylene, FEP)，其即使於高溫及高 鲁濕度下仍可提升穩定的駐極體特性。然而，含氟聚合物可 能較昂貴且需要特定的製程技術。含氟聚合物表面具有低 的摩擦係數，致無緊抓或黏附·•鬆脱（stick_siip)特性，因此， 运些含氟1合物無法緊密黏合金屬且不適合用來製成駐極 體揚聲器系統中的一駐極體振動板。已知亦可由非氟聚合 物製作駐極體，例如聚苯乙烯(p〇lystyrene，pS)、聚碳酸酯 樹月曰（polycarbonate, PC)、聚氯乙烯（p0】yVinyi chl〇ride， • pVQ、聚甲基丙烯酸曱酉旨（poiymethylmethacrylate，PMMA) 及％烯烴共聚合物（cyclic 0]efill cop〇iymer，c〇C)。上述這 些非氟聚合物應用於製作駐極體振動板時是較含氟聚合物 應用於製作駐極體揚聲器容易得多。然而，由這些非氟聚 5物製作的駐極體的最初高表面電壓，會相當快速地下 降，特別於高濕度時。因此，實有必要製作一種非氟聚合 物駐極體，其駐極體特性可維持一較長時間週期。 ^美國專利第4,65七546號及第6,852,4〇2號揭露一種由 .两缔製作·的多孔鐵駐極體薄膜（cenuiar ferroeiectret film) ’在電暈充電的過程中，電場導致每一聚合物晶胞内 201008304 產生介電崩潰，介電崩潰儲存相同或相異電荷於晶胞的相 對内表面。多孔鐵駐極體的每一晶胞其側壁具有扮演類似 一偶極的空間電荷，因此，多孔鐵駐極體扮演類似一偶極 駐極體，其具有一大偶極矩且較固態駐極體具有更佳駐極 體特性。 習知技藝中，多孔鐵駐極體的孔洞是由包含例如矽酸 鹽微細外來顆粒的聚合物進行聚合物高度拉伸時自發性開 孔所形成的。同時或依序以兩垂直方向拉伸，以形成具有 •透鏡形狀孔洞的薄膜。由於電漿電子無法足夠加速，以離 子化氣體分子，致孔洞對於藉由内部微電漿放電的有效充 電來說常常太過淺碟。此外，當使用一薄膜拉伸技術製作 一多孔鐵駐極體時，薄膜厚度的控制亦相當困難。 【發明内容】 本發明之一實施例，提供一種駐極體薄膜的製作方 法，包括：提供一含聚合物之溶液，該含聚合物之溶液包 括至少一聚合物材料，至少一溶劑，以及至少一介面活性 劑；塗覆該含聚合物之溶液，以提供一濕潤聚合物薄膜； 移除該濕潤聚合物薄膜中至少一部分之溶劑，以提供一聚 合物薄膜；以及對該聚合物薄膜進行一電暈充電，以形成 該駐極體薄膜。 本發明之一實施例，提供一種揚聲器，包括：一音頻 訊號輸入，其具有一第一訊號源端與一第二訊號源端，該 音頻訊號輸入用以接受一音頻訊號；兩電極，被設置為彼 201008304 此分離；以及一駐極體薄膜，包括至少一駐極體層（electrei layer) ’且遠端耦合於該兩電極之間。值得注意的是，該兩 電極之一第一電極與該第一訊號源端耦合，該兩電極之一 第二電極與該第二訊號源端耦合。該駐極體薄膜與該第一 電極及該第二電極相互作用，以回應由該第一訊號源端與 該第一訊號源端提供的音頻訊號。此外，該駐極體薄族藉 由振動以產生聲音。在一實施例中，該駐極體層包括一聚 合物層’其具有複數個孔洞且由一濕潤聚合物薄膜所形成。 • 為了讓本發明能更明顯易懂，下文特舉實施例，並配 合所附圖示，作詳鈿說明如下： ：[實施方式】 本發明之一實施例中，可於非氟聚合物薄膜内產生孔 洞，藉此改善非氟聚合物駐極體薄膜的駐極體特性。在一 實施例中，孔洞形狀可類似球狀，且其内表面可包含部分 放電。一駐極體揚聲器可由一非氟聚合物駐極體薄膜的駐 應 極體振動板所製作。本發明之一實施例，可提供一種多孔 非氟聚合物駐極體薄膜的製作方法。 本發明之一實施例係關於一非氟聚合物駐極體薄膜， 其由一含聚合物的溶液所形成。含聚合物的溶液可包括至 少一聚合物材料與至少一介面活性劑。聚合物材料可包括 一或多種環烯烴共聚合物（cyclic olefin copolymer, COC)、 聚苯乙稀(polystyrene，PS)、聚碳酸醋（polycarbonate, PC)、 聚曱基丙烯酸甲酯（poly-methylmeth’acrylate, PMMA)、聚氯 201008304 乙稀（polyvinyl chloride, PVC)、聚亞醢胺（polyimide, PI)、聚醚醯亞胺(polyetherimide, PEI)、高密度聚乙稀(high density polyethylene，HDPE)與聚丙烯(polypropylene，PP)。 介面活性劑可包括一或多種（n+1 )-羥基烷酸 ((n+l)-hydroxy-alkanoic acid)、 （n+1)-胺基烧酸 ((n+l)-amino-alkanoic acid)、HO，（ CH2) n-COOH、2,3-雙-(n- 羥基-院氧基）- 琥珀酸 (2,3-1^(11-117(11'〇义>^11<：)4〇又5〇-511(^111〇3(^(1)、2,3-雙-(11-胺 •基-烷氧基） -琥 ί白酸（2,3-bis(n_amino-alkyloxy)-succinic acid)、（ n+1 )-三嗤烧酸((n+l)-triazol-alkanoic acid)、2,3-雙-(η-三唑-烧氧基）-號珀酸 (2,3-bis(n-triazokalkyloxy)-succinic acid)、十二烧基硫酸鈉 (sodium dodecyl sulfate，SDS)、兩性介面活性劑、非離子型 介面活性劑、陰離子型介面活性劑與陽離子型介面活性 劑。為溶解聚合物材料與介面活性劑於溶液形態，於含聚 合物的溶液中可加入一或多種的溶劑，例如丙酮、四負J °夫 籲喃(tetrahydrofuran，THF)、甲苯(toluene)、二甲苯(xylene)、 對二曱苯(p-xylene)、二氯曱烧（dichloTomethane)、三氯曱 霞(chloroform)、η-曱基说洛嗣(n-xnethylpyrrolidone, NMP) 與二曱基曱醯胺(dimethylformamide，DMF)。第2圖顯示一 長鏈疏水碳氫化合物之分子式。此碳氫化合物可具有一高 極性羧酸官能基（carboxylic acid group)[-COOH]於一端；在 另一端’其可為羥基官能基或胺基官能基，因此可生成 (n+1)-羥基烷酸或（!1+1)_胺基烷酸。在本發明之一實施例 中’混合之聚合物溶液可包括經基酸化合物（hydroxyl acid 201008304 compound)，例如8-經基辛酸的介面活性劑與環稀烴共聚合 物的聚合物材料。具體而言，以重量濃度1-10,OOOppm之 經基酸化合物可溶於四氫σ夫D南中而產生溶液A1。重量百分 比濃度0.1-15之環烯烴共聚合物可溶於一溶劑例如甲苯、 二甲苯或對二甲苯中，.以產生溶液B1。在一例子中，環烯 烴共聚合物可為德國TOPAS®環烯烴共聚合物或Arton®環 烯烴共聚合物中的至少一個，包括但不限於品級8007、 60B、5013、5017與6017。溶液A1和B1根據一定比例 • 進行混合，使得所得混合之聚合物溶液中，溶液A1以重 量計算約為0.01-30,OOOppm。在一實施例中，8-羥基辛酸 可具有如下之結構ΗΟ-(σΗ2)η<ΟΟΗ , n=7。 在本發明之另一實施例中，混合之聚合物溶液可包括 羥基酸化合物，例如8-羥基辛酸的介面活性劑與聚苯乙 烯、聚碳酸酯、聚氯乙烯與聚曱基丙烯酸曱酯聚合物材料 中至少一種。具體而言，l-l〇,〇〇〇ppm之羥基酸化合物可溶 解於例如二氯甲烷或三氯曱烷溶液中以產生溶液A2。聚合 ❹ 物，如聚苯乙烯、聚碳酸酯、聚氯乙烯或聚甲基丙烯酸甲 酯，以0.1-10重量百分比溶解於一溶劑以形成溶液B2-1、 B.2-2、B2-3與B2-4。在一例子中，溶劑可為三氯曱烷。溶 液A2可以與溶液B2-1、B2-2、B2-3或B2-4按一定比例 混合，使所得混合之聚合物溶液中，溶液A2以重量計算 約為 0.01-30,OOOppm。 第3圖顯示一長鏈疏水碳氫化合物之分子式。此碳氫 化合物具有兩個高極性羧酸官能基[-COOH]於一端；在另 一端，其可具有羥基官能基或胺基官能基，因此可生成.2,3- 10 201008304 雙-(η-羥基-烷氧基）琥珀酸與2,3-雙-(η-胺基-烷氧基） 琥珀酸。在本發明另一實施例中，混合之聚合物溶液可包 括2,3-雙-(η-羥基-烷氧基）琥珀酸與2,3-雙-(η-胺基-烷 氧基）的至少一種。以重量計算l-10,000ppm的.2,3 -雙-(H-.經基-烧氧基）-號ίό酸或雙.-_(n-胺基-院氧基）-破 珀酸可溶解於溶劑中，以形成溶液A3。在一實施例中，溶 劑可為四氫呋喃、二氯曱烷或三氯曱烷。溶液A3可以與 B2-1、B2-2、B2-3或B2-4按一定比例混合，使所得混合 鲁之聚合物溶液中，溶液A3以重量計約為0.01-30,0QOppm。 在一實施例中，利用一含聚合物的溶液製作一駐極體 薄膜的方法可包括以下步驟。將大約15wt%的Topas®環烯 烴共聚合物8007小球溶於一甲苯溶液（例如曱苯，Acros， 99%，密度約0.866g/mL)。加熱上述溶液至80°C及/或攪 拌，以提供溶液A。於室溫（約25°C)下，將大約〇.〇1〜lwt°/〇 的8-經基辛酸溶於四氳呋喃（例如四氫吱喃，Aldrich, 99%， 密度約0.899g/mL)，以提供溶液B。溶液A與溶液B可以 • 95〜5的重量比混合。在一實施例中，將混合溶液置於一攪 拌器約10分鐘與一超音波裝置(例如超音波攪拌器或清洗 器）約5分鐘，得到溶液C。 將溶液C旋轉塗佈於一銅箔基板，例如利用一旋轉塗 佈裝置，以大約l,500rpm的條件操作約2次，每次約20 秒，以提供一濕潤聚合物薄膜。濕潤聚合物薄膜以室溫或 20〜25°C乾燥約30分鐘，亦可置於一真空烘箱（約0.1托） 或一壓力低於大氣壓的烘箱中加熱約8小時。薄膜中大部 分或全部的溶劑或水會蒸散，可得到一具有平均尺寸約1 201008304 微米孔洞的聚合物薄膜。在一實施例中，多孔聚合物薄膜 的厚度約為8土1微米。 於薄膜形成後，進行一充電製程，例如在一實施例中， 利用一具有一針板(偏壓-20KV)的放電裝置，以形成一駐極 體薄膜。放電板或針與薄膜之間的距離大約可為4公分。 在一實施例中，充電製程可在溫度約2〇〜25〇c，相對濕度 (relative humidity，RH)約45〜50%的條件下進行。溫度、距 離、相對濕度及放電偏壓可依據不同因素加以調整，例如 鲁上述參數值、其他外部條件、薄膜材料、厚度或性質及預 期的駐極體特性。 在一實施例中，利用一含聚合物的溶液製作一駐極體 薄膜的方法可包括以下㈣。將大約環歸 趄共笨合物8007小球溶於一甲苯溶液（例如甲苯， 99%，，度約〇.g66g/mL)。加熱上述溶液至肋工及/或搜5 拌，以提供溶液Αβ於室溫（約25。〇下，將大約lwtG/(^ 心 ❹硫醇己基）丙一酸(2-(6-mercaptohexyl)malonic acid)溶於四 氫呋喃（例如四氫呋喃，Aldrich, 99%,密度約0.899g/mL)， 以提供溶液B。溶液A與溶液B可以90〜10的重量比混合。 在一貫施例中，將混合溶液置於一攪拌器約10分鐘與〜超 音波裝置（例如超音波授拌器或清洗器）約5分鐘，得到 液C。 Λ 將溶液C旋轉塗佈於一銅箔基板，例如利用一旋轉塗 佈裝置，以大約的條件操作約2次，每次約如 秒，=提供—濕潤聚合物薄膜。濕潤聚合物薄膜以室邃或 20〜25 C乾燥約30分鐘，亦可置於一真空烘箱（約〇1托） 12 201008304 或一壓力低於大氣壓的烘箱中加熱約8小時。薄膜中大部 分或全部的溶劑或水會蒸散，可得到—具有平均尺寸約1〇〇 奈米孔洞的聚合物薄膜。在-實施例中，多孔聚合物薄膜 的厚度約為8±1微米。 於薄膜形成後，進行一充電製程，例如在一實施例中， 利用-具有—針板(偏壓·避V)的放電裝置，⑽成一駐極 體薄膜。放電板或針與薄膜之間的距離大約可為4公分。 在只知例中’充電製程可在溫度約20〜25 〇C ,相對濕度 • (relative h贿idity，RH)約45〜50%的條件下進行。溫度、距 離、相對濕度及放電偏壓可依據不同因素加以調整，例如 上述參數值、其他外部條件、薄膜材料、厚度或性質及預 期的駐極體特性。 在一貫施例中，利用一含聚合物的溶液製作一駐極體 薄膜的方法可包括以下步驟。將大約15wt%的T〇pas⑧環烯 烴共聚合物8007小球溶於一甲苯溶液（例如曱苯，Acr〇s， 99%，密度約〇.866g/mL)。加熱上述溶液至80〇c及/或攪 拌，以提供溶液A。於室溫（約25。〇下，將大約 2-(10-羥基癸基）丙二酸(2_(10_办扣〇?^和叮丨)1^1〇1^肛1句 溶於四氫呋喃（例如四氫呋喃，Aldrich，99%,密度約 〇.899g/mL) ’以提供溶液B。溶液A與溶液B可以95〜5的 重量比混合。在一實施例中，將混合溶液置於一攪拌器約 10 /刀鐘與一超音波裝置（例如超音波攪拌器或清洗器）約5 分鐘’得到溶液c。 •將溶液C，旋轉塗佈於一銅落基板，例如利用一旋轉塗 佈裝置，以大約l,500rpm的條件操作約2次，每次約 13 201008304 秒，以提供一濕潤聚合物薄膜。濕潤聚合物薄膜以室溫或 20〜25°C乾燥約30分鐘，亦可置於一真空烘箱（約0.1托) 或一壓力低於大氣壓的烘箱中加熱約8小時。薄膜中大部 分或全部的溶劑或水會蒸散，可得到一具有平均尺寸約400 奈米孔洞的聚合物薄膜。在一實施例中，多孔聚合物薄膜 的厚度約為8±1微米。 於薄膜形成後，進行一充電製程，例如在一實施例中， 利用一具有一針板(偏壓-20KV)的放電裝置，以形成一駐極 • 體薄膜。放電板或針與薄膜之間的距離大約可為4公分。 在一實施例中，充電製程可在溫度約20〜25°C，相對濕度 (relative humidity，RH)約45〜50%的條件下進行。溫度、距 離、相對濕度及放電偏壓可依據不同因素加以調整，例如 上述參數值、其他外部條件、薄膜材料、厚度或性質及預 期的駐極體特性。 在本發明之一實施例中，混合之聚合物溶液可包括至 少兩種不同之聚合物溶液。重量百分比為1-15的環烯烴共 • 聚合物可溶解於溶劑中以形成溶液A4。不同類型的聚合物 材料，如聚苯乙烯可溶解於溶劑中以形成溶液B4。在一例 子中，溶劑可以是甲苯、二甲苯與對二甲苯中的至少一種。 以適當比例混合溶液A4和B4，由此得到一混合溶液。在 乾燥與電暈充電（corona charge)製程後，可以觀察到混合聚 合物的表面電壓較原始聚合物的表面電壓有所增加。第5 圖為顯示環烯烴共聚物和聚苯乙烯混合物的表面電壓的曲 線圖。如第5圖所示，混合之環烯烴共聚合物/聚苯乙.烯於 一 85/15或15/85的比例中，其表面電壓至少增加190%。 201008304 可以發現，混合聚合物具有結晶介面，且因此改善電荷儲 存能力與穩定度。 在一實施例中，聚碳酸酯、聚曱基丙烯酸曱醋與聚氯 乙烯之至少一個可溶於一溶劑，例如甲苯、二曱苯或對二 曱苯中。此外，聚乙烯與聚丙烯之至少一個在約12(rc溫度 下溶解於對二曱苯中，以一適合的比例將這些溶液進行混 合，由此產生一混合溶液。與上述實施例相似，在另一實 施例中，聚亞醯胺與聚醚醯亞胺可溶於一溶劑中，例如n_ φ 曱基呲咯酮或二曱基曱醯胺，以一適合的比例將這些溶液 進行混合，由此產生一混合溶液。 在本發明另一實施例中’於上述實施例中提到的聚合 物溶液可包括或更包括一高極性緩酸[_C〇〇H]，以改善駐 極體性質。在一實施例中，於上述實施例所提到的聚合物 溶液可塗覆於一不織布（non-woven)材料上，如聚乙烯 (polyethylene，PE)、聚丙烯(polypropylene, PP)、聚對苯二 曱酸乙二酯（poly(e1;hylene terephthalate)，PET)、尼龍 ❿ （nylon)、聚丙烯與尼龍的混合物或聚丙稀與聚對苯二甲酸 乙二酯的混合物。在一實施例中，聚合物溶液可更包括奈 米尺寸顆粒或微米尺寸纖維。在一例子中，顆粒或纖維可 為聚對苯二甲酸乙稀醋（p〇ly(ethylene terephthalate), PET)、聚四氟乙烯(polytetrafluoroethylene, ΡΙΓΕ)、氟化乙 丙烯（fluorinated ethylene propylene, FEP)、二氧化石夕（silicon dioxide)、氧化鋁、二氧化鈦與高密度聚乙烯的至少一種。 為製成辱極體層，可利用旋轉塗佈（spin coating)、網版 印刷（screen-printing)、噴霧塗佈（spraying coating)、濺鐘、 15 201008304 蒸鍍與刮刀塗佈（scraping)技術的至少之一务覆上、， 液於-表面或一下方層’以形成一濕潤聚合物$混合溶 例如於一受控制環境或一控制溫度中乾 、。之後 又T祀知此濕潤人 膜。在一實施例中，可提供一溫度20〜25 D物缚 ^ -¾ i®· 3 Ab —. 可改變環境條件，以控制乾燥製程，例如使用一 “、、而， 的烘箱。乾燥製程允許移除濕潤聚合物薄骐中至:上二述 的溶劑，以提供一聚合物薄膜。在乾燥製程中，*邻刀 高極性化合物可形成-自我組裝(seif_assembUng) t物與 具有於奈米至微米尺寸範圍之孔洞。在一實施例^ ，其 述製程所形成的聚合物薄膜具有複數個尺寸介二約I =亡 的孔洞.，例如10奈米至約10微米。此種結構可择丈，米 聚合物之駐極體區域。 胃”吧合 在—實施例中’當介面活性劑濃度高於臨界微胞滚声 (critical micelle concentration，CMC)時，於含聚合物 y w 又 中會形成聚合物/介面活性劑徵胞，而形成的孔洞在=冷， 充電過程中可維持介電崩潰，改善魏聚合物駐極體^ 的駐極體特性。在一實施例中，聚合物材 ，、 的重量比約為o.〇1〜1〇w 七、"面活性劑 此外，藉由一充電製程可改善聚合物層之 或導入聚合物層的電荷’例如一電暈充電製程’。一：：性 極體薄膜可藉由上述揭露的製程而形成。在―例子十氣駐 將^烤煙共聚合物之駐極體特性提高至14〇%，如 可 所不。可藉由連續式捲繞⑽丨魯_製㈣ = β> ^ Jfr, A m rb A 駐·極體 ^刚與lb。形成之駐極體層的厚度約為 υ·ί5-1〇〇μιη 〇 16 201008304 參見第4圖，薄膜4包括兩個駐極體層la與ib及— 位於駐極體層la與lb之間的導電層2。駐極體層可利用 上述相關之製程來形成。導電層2可為金、銀、鋁、銅或 其他導電材料來製成。可藉由喷霧塗佈（spraying coating)、 旋轉塗佈、藏鑛（sputtering)、蒸鍍（evaporation)與網版印刷 製程中的至少一種將導電層2覆蓋於駐極體層la上，以形 成結構3。在一實施例中，使用電子東蒸鍍（e-beam evaporator)將金屬層蒸鍍至駐極體層上。經由一真空熱壓 • 合(vacuum thermal compression)、機械壓合或連續式捲繞 (roll-to-roll)製程技術將駐極體層lb形成於結構3之上’以 形成一駐極體-金屬-駐極體薄膜。一電暈充電製程可增加 薄膜4之電荷儲存穩定度。在此考量下，薄膜4可適用於 如駐極體#聲器使用之振動板。在一例子中，一靜電揚聲 器包括薄膜4與兩電極，電極與一音頻訊號輸入電性耦 合。電極具有開口以允許聲波通過開口。薄膜4被夾在電 極之間，且各個電極與薄膜4之間都具有氣隙。薄膜4可 為一與電極遠端耦合且與電極絕緣的促動器，以便與電極 相互作用，回應來自音頻訊號輸入的音頻訊號，並振動以 產生聲波。 雖然本發明已以實施例揭露如上，然其並非用以限定 本發明，任何熟習此技藝者，在不脫離本發明之精神和 範圍内，當可作些許之更動與潤飾，因此本發明之保護 範圍當視後附之申請專利範圍所界定者為準。 17 201008304 【圖式簡單說明】 第1圖為先前技術之駐極體揚聲器的斷面圖。 第2圖為一疏水壤氫化合物之分子式。 第3圖為一疏水碳氫化合物之分子式。 第4圖顯示本發明一實施例駐極體揚聲器之部分斷面 圖。 第5圖為一曲線圖，其顯示環烯烴共聚合物與聚苯乙 烯之混合物的表面電壓。 • 第6圖為一表格，顯示於不同厚度中環烯烴共聚合物 與混合之環烯烴共聚合物之表面電價。 【主要元件符號說明】 la、lb〜駐極體層 2〜導電層 3〜結構 4〜振動板或薄膜 5a、5b〜支持構件 51a、51b、52a、52b〜絕緣元件 6a、6b〜多孔電極 61a、61b〜開口 7a、7b〜訊號源 8a、8b〜導線 18201008304 VI. Description of the Invention: TECHNICAL FIELD OF THE INVENTION The present invention relates to electret materials, and more particularly to an electret speaker and method of fabricating the same. [Prior Art] An electrostatic speaker according to coulomb's law, and two conductors having different or identical charges can generate a push or pull force. The alternating push-pull electrostatic force can cause vibrations with static charge diaphragms and thus produce sound. An electrostatic speaker typically includes two porous conductive plates or electrode plates and a vibrating plate interposed between and driven by the conductive plates or electrode plates. An aiT gap separates the electrode from the diaphragm to provide room for vibration of the diaphragm. The vibrating plate is usually thin and light, and thus causes a transient response of the electrostatic speaker, an expansion capabiiity, a sound fluency (sm〇〇 also ness 〇f sound), and a sound fidelity ( Acoustic fidelity) and low distortion 'better than other forms of speakers, such as dynamic, mwingcoil or piezoelectric speakers. In addition, the vibrating plate must have an electrostatic charge to allow the induced electrostatic force to drive the vibrating plate under the action of the electric field formed by the electrode plate when the signal is transmitted to the electrode plate. Due to the simple structure, the electrostatic speaker can be manufactured in a variety of sizes to accommodate the increasing demand for small and thin electronic devices. However, the general electrostatic speaker uses a DC-DC converter (DC_DC e〇nverter) to provide static charge on the diaphragm formed by the conductor. Considering the size, cost and power consumption of DC-to-DC converters, electret materials have been developed to replace DC-to-DC power converters in 201008304. The electret is a dielectric material having a quasi-permanent or dipole polarization. An electret produces internal and external electrical, which can be an electrostatic equivalent of a permanent magnet, see G. M. Sessler K 198 Top in Topics in Applied Physics vol. 33 Chapter 1! Pages and U.S. Patent No. 4,288,584 (Mishra). The electret charge can include a net charge (e.g., surface and/or space charge) and/or dipole polarization. The net charge includes a capture and a negative charge carrier layer. An exemplary electret speaker is shown in Fig. i, which may include a plurality of aperture electrode plates 6a and 6b and an electret diaphragm 4. The electrodes 6a and 6b may have openings 61a and 61b and have an opening ratio of at least 3% at each electrode plate. The electrode plates 6a and 6b may be formed of metal or a plastic material covering the conductive thin crucible. The openings 61a and 61b can provide passage of sound waves. The electret vibrating plate 4 may include a conductive layer 2 which is lost between the electret layers 1& and lb. The electret layers la and lb may include a positive or negative charge or may be positioned to have a relative dipole polarization in the vertical direction of the electret vibrating plate 4. The electrode plates 6a and 6b and the electret vibrating plate 4 can be maintained in a suitable place by the supporting members 5a and 5b. The support member 5a can be made of an insulating material. The electrode plates 6a, 6b can be separated from the electret diaphragm by the insulating members 51a, 51b, 5.2a and 52b. In the operation of an electret speaker, each signal source and 7b output an alternating signal to the electrode plate 6b via wires 8& and 8b, respectively. The signal causes a time-Varying eleciric fieId to develop between the electrode plates 6& and 6b and the electret layer u and the ratio, and an electrostatic force is generated between the electrode plates 6b and the electret vibrating plate 4. The electrostatic force causes the electret diaphragm 4 to vibrate to produce sound. The generated sound waves can pass through the holes 61a and 61b'. Therefore, the sound waves can be heard outside the electret speakers. 201008304 However, in order to enhance the acoustic fidelity and low distortion of electret speakers, it requires an electret material with excellent electret characteristics that requires careful handling. The process is to fabricate a thin electret-metal-electret structure. It is known that electrets can be made from different polymers. Charge is generated in the polymer electret film by a continuous corona treatment. The above different polymers include fluoropolymers, such as poly-tetrafluoroethylene (PTFE) and fluorinated ethylene propylene (FEP), which can improve stability even at high temperatures and high humidity. Electret characteristics. However, fluoropolymers can be expensive and require specific process technologies. The surface of the fluoropolymer has a low coefficient of friction, resulting in no sticking or sticking/sticking (stick_siip) characteristics. Therefore, some fluorine-containing compounds cannot adhere to metals and are not suitable for making electret speaker systems. An electret diaphragm in the middle. It is also known to make electrets from non-fluoropolymers, such as polystyrene (pS), polycarbonate polycarbonate (PC), polyvinyl chloride (p0) yVinyi chl〇ride, • pVQ , poiymethylmethacrylate (PMMA) and % olefin copolymer (cyclic 0)efill cop〇iymer, c〇C). These non-fluoropolymers are used in the production of electret vibrating plates. Fluoropolymers are much easier to use for making electret speakers. However, the initial high surface voltage of electrets made from these non-fluorinated poly materials can drop quite rapidly, especially at high humidity. It is necessary to make a non-fluoropolymer electret whose electret characteristics can be maintained for a longer period of time. ^ U.S. Patent Nos. 4,65,546 and 6,852,4,2, the disclosure of which is incorporated herein by reference. ·Cenuiar ferroeiectret film' During the corona charging process, the electric field causes a dielectric breakdown in 201008304 in each polymer cell, and the dielectric collapses to store the same or different charges in the unit cell. Relative inner surface. Each cell of the iron-iron electret has a space charge that acts like a dipole. Therefore, the porous iron electret acts like a dipole electret with a large dipole moment and a solid-state electret. The body has better electret characteristics. In the prior art, the pores of the porous iron electret are formed by spontaneous opening of the polymer when the polymer is highly stretched by a polymer containing, for example, fine foreign particles of citrate. Or sequentially stretching in two perpendicular directions to form a film having a lens-shaped hole. Since the plasma electrons cannot be sufficiently accelerated to ionize gas molecules, the pores are often used for effective charging by internal microplasma discharge. In addition, when a porous iron electret is fabricated using a film stretching technique, the control of the film thickness is also quite difficult. [Invention] An embodiment of the present invention provides an electret film. The manufacturing method comprises: providing a polymer-containing solution, the polymer-containing solution comprising at least one polymer material, at least one solvent, and at least one surfactant; coating the a solution of the polymer to provide a wet polymer film; removing at least a portion of the solvent from the wet polymer film to provide a polymer film; and subjecting the polymer film to a corona charge to form the electret The present invention provides a speaker, comprising: an audio signal input having a first signal source end and a second signal source end, the audio signal input for receiving an audio signal; , is set to be the separation of the 201008304; and an electret film comprising at least one electrei layer 'and a distal end coupled between the two electrodes. It is noted that one of the two electrodes is coupled to the first signal source, and one of the two electrodes is coupled to the second signal source. The electret film interacts with the first electrode and the second electrode to respond to an audio signal provided by the first signal source and the first signal source. In addition, the electret family is vibrated to produce sound. In one embodiment, the electret layer comprises a polymer layer' having a plurality of pores and formed from a wet polymer film. In order to make the invention more apparent, the following specific embodiments, together with the accompanying drawings, are described in detail below: [Embodiment] In one embodiment of the present invention, a non-fluoropolymer film can be used. Holes are created therein to improve the electret characteristics of the non-fluoropolymer electret film. In one embodiment, the shape of the hole may be spherical like and the inner surface may comprise a partial discharge. An electret speaker can be fabricated from a resident polar body diaphragm of a non-fluoropolymer electret film. In one embodiment of the present invention, a method of making a porous non-fluoropolymer electret film can be provided. One embodiment of the invention is directed to a non-fluoropolymer electret film formed from a polymer-containing solution. The polymer-containing solution can include at least one polymeric material and at least one surfactant. The polymer material may include one or more cyclic olefin copolymers (COC), polystyrene (PS), polycarbonate (PC), poly-methylmethacrylate (poly-methylmeth). 'acrylate, PMMA), polychlorinated 201008304, polyvinyl chloride (PVC), polyimide (PI), polyetherimide (PEI), high density polyethylene (HDPE) ) with polypropylene (PP). The surfactant may include one or more of (n+1)-hydroxyalkanoic acid ((n+l)-hydroxy-alkanoic acid), (n+1)-amino succinic acid ((n+l)-amino-alkanoic Acid), HO, (CH2) n-COOH, 2,3-bis-(n-hydroxy-homoyloxy)-succinic acid (2,3-1^(11-117(11'〇义>^11<lt ;:)4〇5〇-511(^111〇3(^(1),2,3-bis-(11-amine•yl-alkoxy)-succinic acid (2,3-bis( N_amino-alkyloxy)-succinic acid), (n+1)-tritercinic acid ((n+l)-triazol-alkanoic acid), 2,3-bis-(η-triazole-alkoxy)- 2,3-bis(n-triazokalkyloxy)-succinic acid, sodium dodecyl sulfate (SDS), amphoteric surfactant, nonionic surfactant, anionic surfactant and a cationic surfactant. In order to dissolve the polymer material and the surfactant in a solution form, one or more solvents such as acetone, tetra-negative J ° tetrahydrofuran (THF) may be added to the polymer-containing solution. Toluene, xylene, p-xylene, dichlotomethane, chloroform, η-曱N-xnethylpyrrolidone (NMP) and dimethylformamide (DMF). Figure 2 shows the molecular formula of a long-chain hydrophobic hydrocarbon. This hydrocarbon can have a highly polar carboxylic acid function. A carboxylic acid group [-COOH] at one end; at the other end it can be a hydroxy functional group or an amine functional group, thus producing (n+1)-hydroxyalkanoic acid or (!1+1)-amine Alkanoic acid. In one embodiment of the invention, the 'mixed polymer solution may include a polymerization of a trans-acid copolymer (hydroxyl acid 201008304 compound), such as an 8-octanoic acid interfacial surfactant and a cycloaliphatic copolymer. Specifically, the transbasic acid compound having a weight concentration of 1-10,0 ppm is soluble in tetrahydro sigma D to produce solution A1. The cycloolefin copolymer having a concentration of 0.1-15 by weight is soluble. a solvent such as toluene, xylene or p-xylene to produce solution B1. In one example, the cycloolefin copolymer may be at least one of a German TOPAS® cycloolefin copolymer or an Arton® cycloolefin copolymer. One, including but not limited to grades 8007, 60B, 5013 5017 and 6017. The solutions A1 and B1 are mixed according to a certain ratio, so that the solution A1 in the obtained mixed polymer solution is about 0.01 to 30 ppm by weight. In one embodiment, the 8-hydroxyoctanoic acid may have the structure ΗΟ-(σΗ2)η<ΟΟΗ, n=7. In another embodiment of the present invention, the mixed polymer solution may include a hydroxy acid compound, such as an 8-hydroxyoctanoic acid surfactant, polymerized with polystyrene, polycarbonate, polyvinyl chloride and polydecyl methacrylate. At least one of the materials. Specifically, l-l 〇, 〇〇〇ppm of the hydroxy acid compound can be dissolved in, for example, a dichloromethane or trichloromethane solution to produce a solution A2. A polymeric chelating agent such as polystyrene, polycarbonate, polyvinyl chloride or polymethyl methacrylate is dissolved in a solvent in an amount of 0.1 to 10% by weight to form a solution B2-1, B.2-2, B2-3. With B2-4. In one example, the solvent can be trichlorodecane. The solution A2 may be mixed with the solution B2-1, B2-2, B2-3 or B2-4 in a certain ratio so that the solution A2 in the obtained mixed polymer solution is about 0.01 to 30 ppm by weight. Figure 3 shows the molecular formula of a long chain hydrophobic hydrocarbon. This hydrocarbon has two highly polar carboxylic acid functional groups [-COOH] at one end; at the other end, it may have a hydroxyl functional group or an amine functional group, thus generating .2,3- 10 201008304 bis-(η -Hydroxy-alkoxy)succinic acid and 2,3-bis-(η-amino-alkoxy)succinic acid. In another embodiment of the present invention, the mixed polymer solution may include 2,3-bis-(η-hydroxy-alkoxy)succinic acid and 2,3-bis-(η-amino-alkoxy). At least one of them. 1 -3 - bis-(H-. thio-alkoxy)-thionic acid or bis--(n-amino-homoyloxy)-serperic acid can be 1-10,000 ppm by weight. Dissolved in a solvent to form solution A3. In one embodiment, the solvent can be tetrahydrofuran, dichlorodecane or trichlorodecane. The solution A3 may be mixed with B2-1, B2-2, B2-3 or B2-4 in a certain ratio so that the solution A3 is about 0.01-30,0QOppm by weight in the obtained polymer solution. In one embodiment, the method of making an electret film using a polymer-containing solution can include the following steps. Approximately 15% by weight of Topas® cycloolefin copolymer 8007 pellets were dissolved in a toluene solution (e.g., toluene, Acros, 99%, density about 0.866 g/mL). The above solution was heated to 80 ° C and/or stirred to provide solution A. At room temperature (about 25 ° C), about 8 经 1 ~ lwt ° / 〇 of 8-carboic acid is dissolved in tetrahydrofuran (such as tetrahydrofuran, Aldrich, 99%, density of about 0.899g / (mL) to provide solution B. Solution A and solution B can be mixed in a weight ratio of 95 to 5. In one embodiment, the mixed solution is placed in an agitator for about 10 minutes with an ultrasonic device (e.g., ultrasonic mixer or washer) for about 5 minutes to provide solution C. Solution C is spin coated onto a copper foil substrate, for example, by a rotary coating apparatus, at about 1,500 rpm for about 2 times, about 20 seconds each time, to provide a wet polymer film. The wet polymer film is dried at room temperature or 20 to 25 ° C for about 30 minutes, and may be placed in a vacuum oven (about 0.1 Torr) or an oven at a pressure lower than atmospheric pressure for about 8 hours. Most or all of the solvent or water in the film will evaporate, resulting in a polymer film having an average size of about 1 201008304 micron pores. In one embodiment, the porous polymeric film has a thickness of about 8 soils and 1 micrometer. After the film is formed, a charging process is performed. For example, in one embodiment, a discharge device having a pin plate (bias of -20 kV) is used to form an electret film. The distance between the discharge plate or needle and the film can be approximately 4 cm. In one embodiment, the charging process can be carried out at a temperature of about 2 Torr to 25 〇 c and a relative humidity (RH) of about 45 to 50%. Temperature, distance, relative humidity, and discharge bias can be adjusted based on various factors, such as the values of the above parameters, other external conditions, film materials, thickness or properties, and expected electret characteristics. In one embodiment, the method of making an electret film using a polymer-containing solution may include the following (d). The approximately ring-recombined 8007 pellet was dissolved in a toluene solution (e.g., toluene, 99%, degree about 〇.g 66 g/mL). Heat the above solution to the ribs and / or 5 to provide a solution of Αβ at room temperature (about 25 〇, about 1wtG / (^ heart thiol hexyl) propionate (2-(6-mercaptohexyl) Malonic acid) is dissolved in tetrahydrofuran (eg, tetrahydrofuran, Aldrich, 99%, density about 0.899 g/mL) to provide solution B. Solution A and solution B can be mixed in a weight ratio of 90 to 10. In a consistent embodiment, the mixture will be mixed. The solution is placed in a stirrer for about 10 minutes with a ~ ultrasonic device (such as an ultrasonic mixer or washer) for about 5 minutes to obtain a liquid C. 旋转 Rotating the solution C onto a copper foil substrate, for example using a spin The coating device is operated under about conditions for about 2 times, each time, such as seconds, to provide a wet polymer film. The wet polymer film is dried at room temperature or 20 to 25 C for about 30 minutes, or may be placed in a vacuum. Oven (about 1 Torr) 12 201008304 or a pressure of less than atmospheric pressure in an oven for about 8 hours. Most or all of the solvent or water in the film will evaporate, which can be obtained - with an average size of about 1 nanometer hole Polymer film. In an embodiment, a porous polymer film The thickness is about 8 ± 1 μm. After the film is formed, a charging process is performed, for example, in one embodiment, using a discharge device having a pin plate (biasing and avoiding V), (10) forming an electret film. The distance between the plate or the needle and the film can be about 4 cm. In the case of only the 'charging process, the temperature can be about 20~25 〇C, and the relative humidity (relative h bribe idity, RH) is about 45~50%. The temperature, distance, relative humidity and discharge bias can be adjusted according to different factors, such as the above parameter values, other external conditions, film material, thickness or properties, and expected electret characteristics. The method for producing an electret film using a polymer-containing solution may include the following steps: about 15% by weight of T〇pas8 cycloolefin copolymer 8007 pellet is dissolved in a toluene solution (for example, toluene, Acr〇s, 99%, density about 866.866g/mL). Heat the above solution to 80 ° C and / or stir to provide solution A. At room temperature (about 25 〇, will be about 2-(10-hydroxy fluorenyl) Malonic acid (2_(10_办扣〇?^和叮丨)1^1〇1^ anal 1 sentence soluble Hydrofuran (e.g., tetrahydrofuran, Aldrich, 99%, density about 899.899 g/mL) is used to provide solution B. Solution A and solution B can be mixed in a weight ratio of 95 to 5. In one embodiment, the mixed solution is placed. A stirrer is about 10 / knives and an ultrasonic device (such as an ultrasonic mixer or washer) for about 5 minutes to get the solution c. • Rotate the solution C onto a copper drop substrate, for example using a spin coating The cloth apparatus was operated about 2 times at about 1,500 rpm for about 13 201008304 seconds each to provide a wet polymer film. The wet polymer film is dried at room temperature or 20 to 25 ° C for about 30 minutes, and may be placed in a vacuum oven (about 0.1 Torr) or an oven at a pressure lower than atmospheric pressure for about 8 hours. Most or all of the solvent or water in the film will evaporate, resulting in a polymer film having an average size of about 400 nm. In one embodiment, the porous polymeric film has a thickness of about 8 ± 1 micron. After the film is formed, a charging process is performed. For example, in one embodiment, a discharge device having a pin plate (bias of -20 kV) is used to form an electret film. The distance between the discharge plate or needle and the film can be approximately 4 cm. In one embodiment, the charging process can be carried out at a temperature of about 20 to 25 ° C and a relative humidity (RH) of about 45 to 50%. Temperature, distance, relative humidity, and discharge bias can be adjusted based on various factors such as the above values, other external conditions, film material, thickness or properties, and expected electret characteristics. In one embodiment of the invention, the mixed polymer solution may comprise at least two different polymer solutions. The cyclic olefin co-polymer having a weight percentage of 1 to 15 can be dissolved in a solvent to form a solution A4. Different types of polymeric materials, such as polystyrene, are soluble in the solvent to form solution B4. In one example, the solvent may be at least one of toluene, xylene and p-xylene. The solutions A4 and B4 were mixed in an appropriate ratio, thereby obtaining a mixed solution. After the drying and corona charge process, it was observed that the surface voltage of the mixed polymer increased compared to the surface voltage of the original polymer. Fig. 5 is a graph showing the surface voltage of a cycloolefin copolymer and a polystyrene mixture. As shown in Fig. 5, the mixed cycloolefin copolymer/polystyrene has a surface voltage of at least 190% in a ratio of 85/15 or 15/85. 201008304 It has been found that mixed polymers have a crystalline interface and thus improve charge storage capacity and stability. In one embodiment, at least one of polycarbonate, polydecyl acrylate vinegar, and polyvinyl chloride is soluble in a solvent such as toluene, dinonylene or p-benzoquinone. Further, at least one of polyethylene and polypropylene is dissolved in p-diphenylbenzene at a temperature of about 12 (rc temperature), and these solutions are mixed in a suitable ratio, thereby producing a mixed solution. Similar to the above embodiment, In another embodiment, the polymethyleneamine and the polyetherimine are soluble in a solvent, such as n_φ fluorenyl fluorenone or dimethyl decyl amide, and the solutions are mixed in a suitable ratio. A mixed solution is thus produced. In another embodiment of the invention, the polymer solution referred to in the above examples may include or include a highly polar acid retardant [_C〇〇H] to improve the electret properties. In one embodiment, the polymer solution mentioned in the above embodiments may be applied to a non-woven material such as polyethylene (PE), polypropylene (PP), poly. a mixture of poly(e1;hylene terephthalate, PET), nylon nylon, polypropylene and nylon, or a mixture of polypropylene and polyethylene terephthalate. In the case, the polymer solution may further include a nanometer size. Granular or micron-sized fibers. In one example, the particles or fibers may be polyethylene terephthalate (PET), polytetrafluoroethylene (fluorene), fluorinated ethylene propylene. At least one of fluorinated ethylene propylene (FEP), silicon dioxide, alumina, titanium dioxide, and high-density polyethylene. For the formation of the immersed body layer, spin coating, screen printing can be used. (screen-printing), spray coating, splashing clock, 15 201008304 at least one of vapor deposition and scraping techniques, liquid-on-surface or a lower layer to form a The wet polymer is mixed and dissolved, for example, in a controlled environment or at a controlled temperature, and then the wet human membrane is known. In one embodiment, a temperature of 20 to 25 D is provided. ®· 3 Ab —. The environmental conditions can be changed to control the drying process, for example using an “,” oven. The drying process allows the removal of the wet polymer thinner to: the solvent described above to provide a polymerization Thin film. In the drying process, the *-knife high-polarity compound can form - self-assembled (seif_assembUng) t and pores having a range of nanometer to micron size. In an embodiment, the polymer formed by the process The film has a plurality of pores having a size of about I = dying. For example, from 10 nm to about 10 μm. This structure can be chosen as the electret region of the polymer. The stomach is in the same embodiment - when the concentration of the surfactant is higher than the critical micelle concentration (CMC), the polymer/interactivator is formed in the polymer-containing yw, and The formed hole can maintain the dielectric collapse during the charging process, and improve the electret characteristics of the Wei polymer electret. In one embodiment, the weight ratio of the polymer material is about o. ~1〇w VII, "Face Active Agent In addition, the charge of the polymer layer or introduced into the polymer layer can be improved by a charging process, such as a corona charging process. One:: The polar body film can be used The process disclosed above is formed. In the example, the electret characteristic of the flue-cured copolymer is increased to 14%, as can be achieved by continuous winding (10) 丨 _ _ (4) = β gt ; ^ Jfr, A m rb A resident pole body ^ lb and lb. The thickness of the electret layer formed is about ί·ί5-1〇〇μιη 〇16 201008304 See Fig. 4, film 4 includes two electret layers La and ib and - a conductive layer 2 between the electret layers la and lb. The electret layer can be utilized The related process is formed. The conductive layer 2 can be made of gold, silver, aluminum, copper or other conductive materials. It can be spray coating, spin coating, sputtering, evaporation At least one of an evaporation and a screen printing process covers the conductive layer 2 on the electret layer 1a to form the structure 3. In one embodiment, the metal layer is steamed using an e-beam evaporator. Plating onto the electret layer. The electret layer lb is formed over the structure 3 via a vacuum thermal compression, mechanical press or roll-to-roll process technique. An electret-metal-electret film is formed. A corona charging process can increase the charge storage stability of the film 4. Under this consideration, the film 4 can be applied to a vibrating plate such as an electret. In one example, an electrostatic speaker includes a film 4 and two electrodes, the electrodes being electrically coupled to an audio signal input. The electrodes have openings to allow sound waves to pass through the openings. The film 4 is sandwiched between the electrodes, and the electrodes and the film 4 are There is an air gap between them. The membrane 4 can be an actuator coupled to the distal end of the electrode and insulated from the electrode to interact with the electrode, to respond to an audio signal from the audio signal input, and to vibrate to produce an acoustic wave. Although the invention has been disclosed above by way of example, However, it is not intended to limit the invention, and those skilled in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The definition is subject to change. 17 201008304 [Simple description of the diagram] Figure 1 is a cross-sectional view of a prior art electret speaker. Figure 2 is a molecular formula of a hydrophobic soil hydrogen compound. Figure 3 is a molecular formula of a hydrophobic hydrocarbon. Fig. 4 is a partial cross-sectional view showing an electret speaker according to an embodiment of the present invention. Figure 5 is a graph showing the surface voltage of a mixture of a cyclic olefin copolymer and polystyrene. • Figure 6 is a table showing the surface electricity prices of cyclic olefin copolymers and mixed cyclic olefin copolymers in different thicknesses. [Description of main components] la, lb~ electret layer 2 to conductive layer 3 to structure 4 to vibrating plate or film 5a, 5b to supporting members 51a, 51b, 52a, 52b to insulating members 6a, 6b to porous electrode 61a, 61b~openings 7a, 7b~signal sources 8a, 8b~wires 18