| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently ensure the feeling of volume on an acoustic feeling in low-pitched sound region in an insertion earphone with a BA (balanced armature) type receiver. SOLUTION: A receiver unit 12 has configuration where a receiver body 50 (BA type receiver) is housed in an enclosure 20, wherein a small hole 66a for making the rear space CR of a housing 56 of the receiver body 50 communicate with external space is formed in the housing 56. The enclosure 20 includes a cylindrical frame 32 with a sound guide tube 16 provided at its tip end, and a gasket 36 inserted and fixed from its base end side to the cylindrical frame 32. The receiver body 50 is inserted into and fixed to the gasket 36 so as to separate a sound emitting hole 64a from the small hole 66a. A communication hole 36e for making the sound emitting hole 64a communicate with a sound path 16a of the sound guide tube 16 is formed in the gasket 36. Further, a first hermetically sealed space C1 for back pressure adjustment which communicates with the small hole 66a and is separated from the sound path 16a is formed between the receiver body 50 and the enclosure 20. COPYRIGHT: (C)2008,JPO&INPIT
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