Patent ID: 8855339

Claim:
An electret loudspeaker device, comprising: a diaphragm, comprising: a first electret; a second electret, stacked on one side of the first electret, wherein at least one of the first electret and the second electret is made of a material comprising expanded polytetrafluoroethylene; an electrode layer, stacked on another side of the first electret that is opposite to the second electret; and a polymer layer being made of a hydrophobic material, wherein the second electret is sandwiched between the polymer layer and the first electret, and the first electret is sandwiched between the electrode layer and the second electret; a first spacer being made of an insulating material, wherein the first spacer is disposed between the diaphragm and the first perforated electrode, and supports the first perforated electrode over the diaphragm to define at least a first chamber; and at least one insulative fixture only penetrating the first spacer and the diaphragm, and covered by the first perforated electrode.