| Summary: | 碩士 === 國立臺灣大學 === 工程科學及海洋工程學研究所 === 98 === 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.
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