| 摘要 |
PROBLEM TO BE SOLVED: To provide a speaker capable of accurately detecting an electrostatic capacity formed between a center pole and a voice coil bobbin without being affected by external disturbance noise. SOLUTION: The speaker detects the electrostatic capacity formed between the voice coil bobbin 4 constituted of a nonmetallic pipe body 21 as a base and the center pole 5, a nonmagnetic inner side copper foil 22 and a nonmagnetic inner side copper plating 23 are formed on the inner peripheral face 21a of the pipe body 21, and an outer side copper foil 25 and an inner side copper plating 26 for coating the inner side copper foil 22 and the inner side copper plating 23 are formed on the outer peripheral face 21b of the pipe body 21 across the pipe body 21. Further, an inner side resist 24 is formed on the inner side copper plating 23 and an outer side resist 27 is formed on the outer side copper plating 26 preferably. Moreover, the outer side copper plating 26 is preferably connected to ground. COPYRIGHT: (C)2007,JPO&INPIT
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