| 摘要 |
PROBLEM TO BE SOLVED: To provide a speaker reduced in the occurrence of gap defect or high gap defect, small in size, improved in deep low frequency reproduction and high in input resistance by providing a notch part in a direction where a voice coil is displaced at the time of amplitude-driving a diaphragm provided in the center pole, thereby preventing the voice coil from coming into contact with a center pole. SOLUTION: Since the shape of a speaker is elliptic, vibration modes different in a major axis direction and in a minor axis direction are generated and, thus, the gap defect and high gap defect caused by rolling are induced. Particularly, the rolling is often generated in the major axis direction liable to lost weight balance. Therefore, the center pole 23 is provided with two notch parts 40 in the major axis direction to extend the gap of a magnetic gap 30 in the major axis direction liable to be displaced when a voice coil 28 is amplified, thus the distance between the voice coil 28 and the center pole 23 is secured to prevent the occurrence of gap defect and the high gap defect.
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