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(11) | EP 0 624 049 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A loudspeaker apparatus |
| (57) A yoke (96), which has an inner peripheral wall (96b) formed concentrically with
an outer peripheral wall (96a), is used in a magnetic circuit of a loudspeaker. A
rare earth element magnet ring (98) is disposed between the outer and inner peripheral
walls of the yoke (96) so as to form a magnetic gap (99) there. Thus, a compact, light
and powerful magnetic circuit is obtained. The magnetic circuit is disposed in front
of a diaphragm (103), which reduces the thickness of the loudspeaker. By making the
projected area of the magnetic circuit on the diaphragm a half or less of the effective
area of the diaphragm, deterioration of the performance properties and the quality
of reproduced sounds can be avoided. Moreover, a heat dissipator (110) is provided
on the yoke (96) so as to prevent any extraordinary or damaging increase in temperature
of a voice coil even when large signals are continuously input to the loudspeaker.
As a result, performance properties of the loudspeaker can be stabilized and reliability
thereof can be enhanced. |