| 摘要 |
PURPOSE:To realize a removal of a peak having no uneveness in characteristic and reduce a distortion due to a power source distortion or other causes by providing an annular structure covering an edge. CONSTITUTION:An equalizer 16 is annular in shape and joined to an opening flange section of a frame 9 and formed so as to cover an outside of an edge 14. In this case, a cavity 17 is constituted by the equalizer 16, the edge 14 and a plane diaphragm 13. A compliance of this cavity 17 and a mass of air of an outlet section 18 generates an acoustic resonance. The formation and the dimension of the equalizer 16 are determined so as to make the resonance frequency coincide with a frequency generating a peak of a frequency response of a plane speaker. The resonance by the compliance of the cavity 17 and the mass of air of the outlet section 18 becomes a parallel resonance in an acoustic circuit, so that a mechanical impedance becomes large, an excessive oscillation in the circumference of the diaphragm is restricted, and a peak on a sound pressure frequency characteristic is deleted with effect. |
