| 摘要 |
PURPOSE:To obtain high rigidity as the entire diaphragm by using two or over of diaphragms (cones) having a different semi-apex angle or curvature in combination so as to make the resonance frequency of each cone different from each other. CONSTITUTION:A frame 5 is coupled to a magnetic circuit comprising a plate 2, a magnet 3 and a top plate 4 and diaphragms 6,7 are coupled to the frame 5 via an edge 8. Then a voice coil 9 is coupled at the middle of the diaphragms 6, 7, the middle part of the coil 9 is held by a damper 10 and fitted to the magnetic gap 11 of the circuit 1 without eccentricity. Moreover, a dust cap 12 is adhered to the middle upper face of the diaphragm 6 so as to avoid the dust in air from entering the gap 11. Since the semi-apex angle or curvature differs from the diaphragms 6, 7, they have different resonance frequencies and a high rigidity as the entire diaphragm is obtained by coupling the boards 6, 7 strongly via the coil 9.
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