| 摘要 |
PURPOSE:To prevent not only unnecessary vibration but also electromotive reproduction of a noise, by filling an air gap made between a microphone unit and its supporting body, with a magnetic fluid, and supporting the microphone unit and the microphone casing in a floating state by said method. CONSTITUTION:The microphone unit supporting lever 12 is inserted into the shaft hole 18 of the yoke 19 from the shaft hole 16 of the yoke 17, the stopper yoke 21 is fitted to the protruding end from this shaft hole 18, and a magnetic circuit is formed, by which the magnetic field is transmitted to the yoke 17, the unit supporting lever 12, the stopper yoke 21 and the yoke 19 in due order. And the gap (a) formed by the end of the microphone unit 11, the unit supporting lever 12 and the shaft hole 16 of the yoke 17, and the gap (b) formed by the unit supporting lever 12, the shaft hole 18 of the yoke 19, and the stopper yoke 21 are filled with the magnetic fluids 22, 23. The microphone unit 11 is supported in a state that it is floating from the microphone casing 14 by utilizing said magnetic fluids 22, 23 as loss materials. In this regard, the space part formed by the magnet 15 and the yokes 17, 19 operates as a sound cavity (c) through the unit supporting lever having the air pit 13. |
