| 摘要 |
PURPOSE:To increase a reproduction frequency band by arranging a voice coil at distance from the lengthwise center of a rectangular plane diaphragm and driving the rectangular plane diaphragm by the voice coil through a joint cone. CONSTITUTION:A voice coil bobbin 3 equipped with the voice coil 9 inserted into and coupled with the root part of the joint cone 11 is positioned (x)mm. away from the center of the rectangular plane diaphragm 1. Therefore, the elliptic opening position of the joint cone 11 is also away from the center of the diaphragm 1 and the oscillating force of the voice coil 9 is assymetrical about the center of the diaphragm 1. Consequently, the resonance mode of the diaphragm 1 which is generated conventionally is suppressed reversely. Further, damping pieces 12 and 13 made of viscoelastic materials are provided on both sides of the rectangular plane diaphragm 1 to damp resonance. Consequently, audio frequency characteristics are flattened to increase the reproduction frequency band. |
