| 摘要 |
PROBLEM TO BE SOLVED: To provide a process by which a charging process to an electret material is performed and a protective structure against impact is formed in a short process.SOLUTION: An electret material 12 is polished from the surface of an electret substrate 14 into a concave-shape during the polishing of the electret material 12. Because the electret material 12 has the concave-shape, it is capable of obtaining a structure that even when a generator is subjected to drop impact and an opposed substrate 40 opposed thereto is deformed, the opposed substrate 40 does not come into contact with the electret material 12. Additionally, a charging process is also performed simultaneously during the polishing by using, as a polishing material, one having a charging property opposite to that of the electret material 12. |
