| 摘要 |
<p>The drive unit has a magnet assembly and a coil assembly comprising a voice coil 3 arranged concentrically with the magnet assembly 5, 6, 7. The magnet assembly comprises a permanent magnet 5 and one or more pole pieces 6, 7. The pole piece 6 is shaped is configured to have a laminated structure comprising at least two spaced layers. The pole piece may include at least three spaced layers, preferably at least four layers 6a, 6b, 6c, 6d. One or more of the layers of the pole piece may be shaped, in at least an region thereof surrounding the magnetic gap, so as to generally follow and guide the magnetic field lines emanating from the permanent magnet. The drive unit may be used as an exciter in a bending wave loudspeaker (figs 1-3).</p> |
