Wideband piezoelectric rectangular loudspeakers using a tuck shaped PVDF bimorph

Piezoelectric loudspeakers are characterized by their very simple structure, however, their sound radiation performance in the low frequency region is poor because their diaphragms are too stiff for large amplitude vibration. In this paper the authors propose an innovative method for improvement of the low frequency radiation performance of piezoelectric direct-radiator loudspeakers. This method involves using a flat-boxy loudspeaker unit with a pleated tuck-shape flexible diaphragm formed of a laminated sheet of PVDF (polyvinylidenfluoride) piezoelectric film. In this paper an explanation of the proposed loudspeaker unit construction is followed by theoretical analysis. Then a few experimental results are shown. Finally a practical multi-way loudspeaker system with satisfactorily wide frequency range for music is constructed by combination of a few loudspeaker units.