| 摘要 |
An electret electrode is constituted by forming a conductive film on a substrate, laminating a first insulating film and a second insulating film alternatively on the conductive film, and then disposing electret films in which a lower surface, an upper surface and a side surface are covered with a third insulating film and a fourth insulating film. Existing of the first insulating film and the second insulating film between the electret films and the conductive film enables an increase in electric field intensity in the film when the same electric charge is retained, while enables an increase in surface charge density (surface potential) when the electric field intensity is the same. |
