| 摘要 |
PROBLEM TO BE SOLVED: To improve radiation of heat generated by a voice coil at the time of energizing in a loudspeaker made lightweight by using a small-sized magnetic circuit. SOLUTION: An opening part 8 is formed nearby the joint part between a magnetic circuit cover 1 and a frame 3 and this opening part 8 is communicated with the back-side space of a diaphragm 4. Consequently, the air inside and outside the loudspeaker moves along the external surface of the magnetic circuit cover 1 without staying due to the back pressure of the diaphragm 4 at the time of energizing, and then a flow of the air continuously absorbs heat conducted from the magnetic circuit 2 to the magnetic circuit cover 1. Further, an air flow passage 10 communicated with the opening part 8 is formed between a large-diameter part 1a projected into the circuit cover 1 and the internal wall surface of the frame 3 and then the heat radiation effect is increased more.
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