| 摘要 |
PURPOSE:To broaden a frequency range and particularly a low band optionally and to realize reduced thickness and light weight by bonding a piezoelectric converter consisting of ceramic piezoelectric element bonded to a thin electrically conductive plate to a flat portion of a diaphragm consisting of a molded film having an annular projection surrounding the central flat portion. CONSTITUTION:A piezoelectric converter 1 consisting of the ceramic piezoelectric element 2 and a thin metallic plate 3 is bonded to a flat central portion of the diaphragm 11 having a central portion 11a and the annular projection 11b surrounding the flat portion and the peripheral portion of the diaphragm 11 is secured to a casing 12. The diaphragm 11 is formed of paper or synthetic resin film of uniform thickness. When a signal is applied to the thus constructed piezoelectric converter 1, there occurs a resultant vibration which is synthesized of the vibration proper to the converter 1 and the vibration of the diaphragm 11 supporting the converter so that the planar wave of the sound is radiated in the arrow mark direction. When the width W of the projection portion 11b is increased gradually, the frequency response of the synthesized vibrations will be increased gradually towards the low band side. |
