Patent ID: 8045745

Claim:
A speaker apparatus comprising: a diaphragm having an effective vibration area S 1 ; and a drive cone having an effective vibration area S 2 , wherein: outer circumferences of the diaphragm and the drive cone are fixed to supporting portions of a frame via a first edge and a second edge respectively; a closed space defined by the diaphragm and the drive cone, the closed space has a volume V; a spring constant of an air spring in the closed space is proportional to (S 1 −S 2 )/V; and the first edge includes at least two ridge portions protruding forward so the spring constant is reduced by reducing a value of (S 1 −S 2 ); and the at least two ridge portions begin at the outer circumference of the diaphragm; wherein each of the ridge portions has an apex angle that is configured to be within a range from 50 to 65 degrees.