| 摘要 |
PURPOSE:To obtain a driver ease of low frequency reproduction and of static attracting force balancing type by increasing the plate outer diameter larger than a ring form permanent magnet so as to increase the suspension outer diameter thereby decreasing stiffness. CONSTITUTION:Since two diaphragms 9a, 9b are arranged with an equal magnetic gap with each exciting part, the static attracting force by permanent magnets 8a, 8b is cancelled together and zero and no stress is exerted to the suspension 17 at the steady-state without any electric signal. The outer diameter of the plates 16a, 16b is increased larger then the outer diameter of the ring form permanent magnets 8a, 8b then the outer diameter of the suspension 17 provided at the outer bottom face of the plates 16a, 16b is increased more than the outer diameter of the permanent magets 8a, 8b so as to decrease the stiffness of the suspension 17. Since the resonance frequency of the electromagnetic driver is decreased independently of the outer diameter of the permanent magents 8a, 8b, when the front face of the diaphragm 9a is fixed to the front panel 3, the low frequency band is expanded remarkably in comparison with conventional speakers. |
