Development of porous electret polymer and its application in electrostatic loudspeaker

In the thesis , we utilized the stable charge storing capabilities of electret to replace the DC to DC converter based biased circuit used in electrostatic loudspeaker and developed an electret speaker. Regarding the elecret materials development, the research efforts concentrated on improving the solution type non-fluoride polymer. Influence of electret properties through mixing heterology polymer and adding the polar molecule into polymer were studied. Through observing the material surface morphology and cross-sections by using scanning electron microscopy and performing materials thermal discharge condition, factors influence the electret properties were discussed. In addition, adhesion between the electret polymer and the metal layer were improved as well. From the experimental results, it was identified that adding specific ratio of polar molecule into polymer can produce the proper porous structure to enhance charge storage capability to -1000 . In the thesis, we successfully utilized porous electret polymer to develop an electret headphone. This newly developed headphone has 400Hz resonance frequency and can achieve 98 sound pressure when driven by 100V signal.