| 摘要 |
PROBLEM TO BE SOLVED: To provide a condenser microphone that can prevent water or various hygrophil germs from intruding. SOLUTION: A mixture of 80±10 wt.% of PTFE(polytetrafluoroethylene) powder with a molecular weight of about 8000, 18±5 wt.% of vinylidene fluoride and 2±1 wt.% of perfluoroether that is diluted with butyl acetate and stired in a ball mill, or a mixture of 79±10 wt.% of PTFE(polytetrafluoroethylene) powder with a molecular weight of about 8000, 18±5 wt.% of vinylidene fluoride, 2±1 wt.% of perfluoroether, photocatalyst anatase-type titanium dioxide fine grain that is diluted with butyl acetate and mixed in a ball mill is used for a water repellent material or an antifouling material in common use with the water repellent material. The material is coated on a sound transmitting material such as a perforated board, unwoven cloth, and a metallic net placed in front of the sound holes of the microphone, or at the back of the sound holes, or at the outside of both. An average radius of the aperture of the sound transmission material is >=1.5% of the cube root of the volume of a space between the sound transmission material and the diaphragm of the microphone and 2 mm or less.
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