| 摘要 |
PURPOSE:To eliminate the need for opening of the bobbin by constituting the tubular bobbin with sponge form metal having open cells. CONSTITUTION:A bobbin 6 made in cylindrical form is made of sponge form metal having open cells and a voice coil 2 is wound on the outside circumference thereof. The air chamber 10 constituted by the center pole 3 of magnetic circuit, dome form diaphragm 4 and bobbin 6 does not cause cavity resonance because the bobbin 6 has air permeability owing to its open cells. |
