PURPOSE: To radiate sound in both font and rear directions with a magnetic circuit as a center and also to reduce leakage magnetic field. ;CONSTITUTION: A ring-shaped magnet 5 is loaded and an annularly magnetic gap 3 is formed in the magnetic circuit 15 where a system is constituted in such a way that an extention end 2a which is obtained by extending the lower end of a center pole 2 which is perpendicularly arranged at the center of an inner part plate 1 to the rear side of the inner plate 1 is formed, the external edge of a top plate 6 is enlarged and extended to the outer part so as to connect it to the external end edge of a bowl-shaped external part york 4, the annular magnetic gap 3 is formed between a center hole provided at the center of the external part york 4 and the extension end 2a of the center pole 2 and the matnetic circuit 15 where the annular magnetic gap 3 is formed is loaded in the front and back surface directions of the ring-shaped magnet 5.;COPYRIGHT: (C)1995,JPO
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