| 摘要 |
PURPOSE:To decrease the sound pressure variation range even if the space distance is changed with a simple constitution and to stabilize the tone quality by supplying to an electromagnet the AC power of a frequency lower than the intrinsic resonance frequency of a diaphragm and driving a vibration system free of the resonance point of a frequency lower than the intrinsic resonance frequency of the diaphragm. CONSTITUTION:The AC magnetic field of the electromagnet consisting of a coil 3 to which the AC power of a frequency lower than the intrinsic resonance frequency of the diaphragm 7 is applied, and of a core 4, and the DC bias magnetic field of a permanent magnet 6 that surrounds the said electromagnet, electromagnetically drive the vibrating system which is free of the resonance point of a frequency lower than the intrinsic resonance frequency of the diaphragm 7, and correspondent sounds are generated. As the result of this constitution, the range of sound pressure variation becomes narrower despite space distances G1 and G2 formed by the top surface 4a of the core 4 and that 6a of the magnet 6 respectively and the diaphragm 7 change. In consequence, the converted sounds having stable tone quality can be produced. |
