Patent ID: 8457345

Claim:
A vibration plate having a voice coil attachment portion, a frame attachment portion and an edge portion which is located between said voice coil attachment portion and said frame attachment portion and has a protruding shape protruding in one direction with respect to said voice coil attachment portion and said frame attachment portion, said edge portion comprising: a center portion; one end located between said center portion and said voice coil attachment portion; and an other end located between said center portion and said frame attachment portion, as seen in a cross section of said vibration plate in a radial direction, said center portion, said one end and said other end each being formed in a circular arc such that said edge portion forms a convex so as to protrude in a direction in which said protruding shape protrudes, and a radius of curvature of the circular arc of said center portion being not less than the radius of curvature of the circular arc of each of said one end and said other end.