| 摘要 |
A magnetic circuit includes an inner permanent magnet assembly and an outer permanent magnet assembly, a magnetically permeable yoke, and first and second air gap portions conducting first and second magnetic flux densities, respectively, the first and second air gap portions being adapted to receive first and second voice coil segments, respectively. The magnetic flux density in the first air gap portion is generated by superposition of magnetic flux generated by the inner permanent magnet assembly and magnetic flux generated by the outer permanent magnet assembly, and wherein the magnetic flux density in the second air gap portion is generated substantially exclusively by the inner permanent magnet assembly. |
