The pole (4) the lower part plate which sudden facilities is done the magnet (3) and ring condition

摘要

PROBLEM TO BE SOLVED: To produce and also to provide a speaker which prevents the eccentricity of a magnet by using a gauge whose structure is sufficiently simple to correspond to a magnet of any inner diameter and has an excellent appearance and high reliability in performance by adding good ideas to the structure of a magnetic circuit top plate and a magnet-positioning means in a manufacturing process. ;SOLUTION: Radial notches 12 whose depth is larger than an inner periphery of a magnet 2 are formed on an inner peripheral part of a central hole that forms a magnetic air-gap 5 of a top plate 1 of an external magnetic type magnetic circuit at more than three places. When the magnetic circuit is assembled, a gauge 6 which has a cylindrical part 61 that secures a mutual positional relation among the plate 1, the magnet 2 and a pole 4 and a positioning protrusion 62 that interfits the notches 12 of the plate 1 and is also projected to the height for containing internal diameter dimensions of the magnet 2 is inserted the inner periphery of the air-gap 5 and the magnet 2, and after adhesive for assembling is solidified, the gauge is removed out.;COPYRIGHT: (C)1998,JPO