| 摘要 |
PROBLEM TO BE SOLVED: To provide a speaker in which a clearance between a yoke and a permanent magnet can be secured wide and reproduction property of an original signal is improved although a voice coil is designed easily.SOLUTION: A speaker comprises a permanent magnet line 111 and a permanent magnet line 115 which are disposed while facing each other. The speaker further comprises a three-phase coil 131 which is disposed between the permanent magnet line 111 and the permanent magnet line 115 and to which a three-phase audio signal is applied, a diaphragm 2 which is vibrated by the three-phase coil 131, and a frame 8 which elastically supports the diaphragm 2 and to which the permanent magnet line 111 and the permanent magnet line 115 are fixed. The permanent magnet line 111 includes permanent magnets 112 in which the directions of magnetic poles are changed by an integral equipartition of 2&pgr; in a specific direction, magnetic fields at a side of the permanent magnet line 115 are strengthened each other and magnetic poles at an opposite side are weakened each other. The permanent magnet line 115 includes permanent magnets 116 in which directions of magnetic poles are changed by an integral equipartition of 2&pgr; in a specific direction, magnetic fields at a side of the permanent magnet line 111 are strengthened each other, and magnetic fields at an opposite side are weakened each other. |
