To provide a laminated sheet for an electret fixing electrode capable of sharply enhancing microphonic sensitivity when used in an electret condenser type microphone, having large charge holding power, excellent in properties as an electret fixing electrode element because of low charge attenuation and also excellent in the adhesiveness with an electret material layer composed of a metal sheet and a polytetrafuloroethylene film.
The laminated sheet for the electret fixing electrode is constituted by thermally welding the polytetrafuluoroethylene film to the surface of the metal sheet to form a first electret material layer and thermally welding the polytetrafuluorethylene film to the surface of the first electret material layer to form a second electret material layer. The film thickness of the first electret material layer is 5-15 μm and the film thickness of the second electret material layer is 10-25 μm.
IWAI SEIICHIRO
KITAJIMA MASAHIRO
Koji Makimura
Chihata Takahata
Toru Suzuki