| 摘要 |
PURPOSE:To miniaturize a magnetic circuit which has a voice coil arranged in the magnetic gap so that it can move freely forth and back by increasing response close to low frequency resonance, by providing the magnetic circuit and a means of transferring the vibration amplitude of the voice coil by expanding it. CONSTITUTION:In the magnetic gap formed between plate magnetic poles 2 arranged facing to center pole 1, voice coil bobbin 6 wound with voice coil 5 is arranged and the tip part of bobbin 6 is linked to lever 8, supported by fulcrum 7 at one end of length l1, at the position of l2 from fulcrum 7. At the position of length l1 from fulcrum 7, diaphragm 9 is linked to lever 8, and the displacement of coil 5 is increased l1/l2 times through the operation of lever 8 and transferred to diaphragm 9. Further, the vibration transfer means of this lever 8 is substituted by a fluid pressure transmission device provided with a cylinder and piston to increase response close to low-frequency resonance as well as the said vibration transfer means, thereby miniaturizing the magnetic circuit. |
