可撓式駐極體揚聲器的研製:創新駐極體材料的開發與應用

Abstract

可撓式揚聲器近年來引起了眾多研究室的興趣，它具有輕薄、節能、可攜式等新的未來的應用範圍，尤其是在新式的平面顯示器紛紛問世之後，更是激發了各界對開發可撓式揚聲器的意願，而確實，已經有許多可撓式的揚聲器被發表出來。 本文對於駐極體材料的探討，將環狀烯烴聚合物(COC, cyclic olefin copolymer)溶液與雙羧基界面活性劑混合後，利用界面活性劑的自組裝機制製作孔洞型環狀烯烴聚合物薄膜；另一方面，使用聚四氟乙烯 (expanded polytetrafluoroethylene, e-PTFE)與COC製作耐高溫的複合駐極體。最後分別討論其材料物理性質、耐溫性與駐電特性。對於溼度相對於駐極體電荷流失，本研究使用聚對二甲基苯(parylene)做為所研製的駐極體之防水保護層，研究顯示具有防止電荷流失的助益。 在揚聲器的結構設計上，是使用蜂巢狀的駐極體揚聲器陣列，並且利用樑的撓曲與板的彎曲理論算出理想的陣列單體尺寸，以達到最佳的效率。而利用計算結果設計出來的平面可撓式駐極體揚聲器陣列的聲場量測結果也呈現在本篇論文中。

Flexible loudspeakers have triggered much interest recently due to the rapidly development of various areas, such as e-books and flexible displays. Furthermore, flexible loudspeakers can be flat, lightweight and portable. Indeed, several research results related to the flexible speakers were reported. In the thesis, cyclic olefin copolymers model 8007 (COC(Topas@8007)) was mixed with double-carboxylic surfactant, the use of surfactant self-assembly mechanism make cyclic olefin copolymers into porous electret film. On the other hand, e-PTFE (expanded polytetrafluoroethylene) and COC were compounded to produce heat-resistant electret. A smart structure had been used to build flexible electret loudspeaker. The structure is similar to honeycomb, but the unit cell is squared instead of hexagonal. This structure could avoid electret membrane touch the electrode when loudspeaker was bending. Furthermore, best size of the unit cell was calculated by modeling electret membrane into beam and plate. In the end of the thesis, the surface potential will be effected by temperature had been observed. Nevertheless, humidity also effected surface potential and it wouldn’t be even less than temperature. The protect layer, parylene, was coating on electret materials to insulate the effect of humidity, and it really achieved good results.