Patent ID: 8259987

Claim:
A diaphragm longer in a longitudinal direction and shorter in a transversal direction in relation to the longitudinal direction, comprising: a base member having a pair of extending members provided in parallel in the longitudinal direction as facing each other, and a curved section that protrudes toward a first side of the diaphragm in a vibration direction of the diaphragm from a first plane that includes the extending members, the vibration direction being perpendicular to the longitudinal and transversal directions; and a slant member having a slant surface in relation to the first plane and connected to the base member in a manner that the slant member surrounds the base member in a second plane parallel to the first plane, the slant member having a curved surface in a cross section thereof in relation to a cross section of the base member in the transversal direction, wherein the slant member has a plurality of concave and convex sections only in a zone of the slant surface, the concave and convex sections having the same curvature and being separated from one another and aligned in the longitudinal direction, and the concave and convex sections being aligned in parallel to a center line of the base member in the transversal direction, the zone corresponding to the extending members of the base member.