| 摘要 |
PURPOSE:To improve the utilizing factor of a coil and to improve the reproducing efficiency, by supporting a long voice coil in a ring shaped magnetic air gap provided to a field section and providing a means short-circuiting the ineffective part of the coil. CONSTITUTION:The ring spahed magnetic air gap is provided between the inner circumference of a top plate 14 of a field section 11 and the outer circumference of a center pole incorporated to a bottom plate 12. The long voice coil 16 is wound on the outer circumference of a voice coil bobbin 15 and supported in the magnetic air gap. A fixed rod having the construction where conductor rods 18-1, 18-2 are linked up and down a fine magnetic substance rod 17 is inserted slidablay through the coil 16. Since the conductor rods 18-1, 18-2 are inscribed to the ineffective winding width of the coil 16, the part is short-circuited electrically. The driving force having good linearity up to a large amplitude region is applied through the consitution like this, and the utilizing factor of the coil 16 is improved, allowing to improve the reproducing efficiency. |
