| 摘要 |
PROBLEM TO BE SOLVED: To adjust a surface voltage charged on an electret dielectric film to a predetermined voltage by a simple technique. SOLUTION: For example, when adjusting an surface voltage charged on an electret dielectric film 23 which is contained on the side of fixed electrode 20 in one united body, compressed air 47 containing alcoholic vapor is sprayed on the whole surface of the electret dielectric film 23 to adjust the surface voltage of the electret dielectric film 23 to a value of the predetermined voltage. COPYRIGHT: (C)2009,JPO&INPIT
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