Speaker with a molded plastic frame including a positioning projection, and a method for manufacturing the same

摘要

A plastic-molded frame 3 has a bottom-closed cylindrical magnetic circuit holding portion 2 which has a positioning projection 6 provided in a central portion on a bottom surface 2a of the magnetic circuit holding portion 2. A magnetic circuit is incorporated in the magnetic circuit holder 2 by putting a bottom plate 9 on the bottom 2a such that a positioning recess 12 in the lower surface of the bottom plate 9 engages the positioning projection 6, next putting a ring-shaped magnet 13 on the bottom plate by using a magnet guide 11 on the bottom plate 9, next putting a top plate 14 on the magnet 13, and next urging the top plate 14 down and rotating it in a predetermined direction such that engaging portions 16 provided along the outer circumferential edge of the top plate 14 engage with engaging projections 8 extending from the upper open end of the magnetic circuit holder 2 and such that slanted surfaces 7 of the engaging projections 8 tightly contract the entirety of the members 14, 13, 9 in the magnetic circuit holder 2.