| 摘要 |
PROBLEM TO BE SOLVED: To provide a speaker in which magnetic efficiency is improved easily even when a low-priced magnet is used for a magnetic circuit, and which is appropriate for reduction in size and in cost.SOLUTION: A magnetic circuit 1 is an inner magnet type, a magnet 10 magnetized in a thickness direction is held between an outer yoke 11 and an inner yoke 12, and a magnetic gap G is provided between an inner peripheral surface of the outer yoke 11 at an open end side and an outer peripheral surface of a flange part 12a of the inner yoke 12. An outer magnetic pole surface 10a of the magnet 10 in tight contact with the outer yoke 11 is a convex hemisphere surface, and an inner magnetic pole surface 10b of the magnet 10 in tight contact with the inner yoke 12 is a concave hemisphere surface but since a radius of the magnetic pole surface 10a is longer than a radius of the magnetic pole surface 10b just by a thickness dimension of the magnet 10, an area of the magnetic pole surface 10a is larger than that of the magnetic pole surface 10b. Furthermore, an end face 10c of the magnet 10 at the open end side is disposed in a position facing the magnetic gap G in a depth direction. |
