| 摘要 |
PROBLEM TO BE SOLVED: To obtain more satisfactory noise cancellation effects. SOLUTION: A conductor part structured to have electric resistance ratio less than that of magnetic body materials configuring a magnetic circuit is arranged near the voice coil of a driver unit so that electromagnetic induction coupling can be generated between the voice coil and the conductor part, and that the inductance of the voice coil can be reduced. The reduction of the inductance of the voice coil reduces a phase difference between a driving voltage to be applied to the voice coil and driving currents corresponding thereto. COPYRIGHT: (C)2008,JPO&INPIT
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