| 摘要 |
PURPOSE: An omnidirectional condenser microphone is provided to reduce a degradation of sound by using a phase delay filter. CONSTITUTION: An omnidirectional condenser microphone includes a case(101) and a printed circuit board(109). A vibration membrane(103), a spacer(104), and an insulation ring(105) are sequentially laminated on a bottom of the case. A back electret(106) is inserted to face the spacer in the insulation ring. The printed circuit board is laminated on an upper portion of a metal ring(107) inserted to an upper portion of the insulation ring. The microphone is inserted and fixed into the insulation ring via the metal ring. The phase delay filter has a thickness between 50 and 400 m and has a hole diameter between 0.025 and 15 m. The phase delay filter is the one selected from a group consisting of a fluorine resin group, an acryl-group, a cellulose group, a polyimide group, a polyester group, a glass fiber and a silica product.
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