| 摘要 |
PURPOSE:To realize the thin profile of a unit and to improve the acoustic transducing efficiency without increasing the resonance frequency of a diaphragm by making the thickness of the center part of the diaphragm or a plate thicker than the thickness of the circumferential part. CONSTITUTION:The relation of t1<t2 is obtained in an electromagnetic speaker, where t1 is the thickness of the diaphragm 9 and t2 is the thickness of a center pole 8. Thus, the magnetic saturation is mostly caused by the diaphragm. Then, in changing the thickness of the center part of the diaphragm 9 from t1 to t2, the cross section to the magnetic flux passing through the diaphragm is increased, the magnetic saturation is reduced remarkably, the magneto-resistance is reduced and the magnetic flux between the diaphragm and the center pole 11 giving a large effect on the acoustic transducing efficiency of the electronic unit is increased, then the efficiency of the speaker is improved without increasing the thickness of the circumference of the diaphragm deciding the resonance frequency of the diaphragm and without increasing the height of the unit. |
