| 摘要 |
The thickness of an electrodynamic speaker equipped with a voice coil of an approximately rectangular roll shape is reduced, and the acoustic characteristics thereof are improved. A plate member (24) is bonded to the upper side of a diaphragm (12), the plate member (24) covering a central region located inside the inner periphery of the voice coil (14). Thus, the height-direction space necessary over the central region is rendered small and the rigidity of the region is enhanced. This plate member (24) comprises a carbon-fiber-reinforced sheet obtained by infiltrating a resin into band-shaped bundles of unidirectionally extending carbon fiber filaments and curing the resin. Consequently, compared to the case where a carbon-fiber-reinforced sheet comprising plain-weave carbon fibers was bonded, the central region is made to have a lighter weight and the height-direction space necessary thereover is made smaller. The plate member is disposed so that the direction in which the carbon fiber filaments extend is the same as the direction in which the minor sides of the peripheral edge (24a) of the plate member (24) extend. The rigidity of the central region is thereby sufficiently ensured.
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