| 摘要 |
PROBLEM TO BE SOLVED: To provide a speaker that can be made low-profile without lowering the performance. SOLUTION: A diaphragm 4 includes a first flat plate 11 whose outer circumferential part is joined with a frame 2 and a second flat plate 13 joined with the first flat plate 11 via an adhesive layer 12. The first and the second flat plates 11, 13 are formed circular and joined with each other by matching the centers with each other. Since the diameter of the second flat plate 13 is smaller than the diameter of the first flat plate 11, an edge part 14 in the absence of the second flat plate 13 is formed to an outer circumferential part of the first flat plate 11. In order to set a shell ratio denoting a ratio of a diameter b of the second flat plate 13 to an effective vibration diameter a of the first flat plate 11 to an optimum value, a lowest resonance frequency fo is reduced and the low-profile speaker with excellent performance can be manufactured, wherein no abnormity sound is caused and an input power can be increased. COPYRIGHT: (C)2007,JPO&INPIT
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