| 摘要 |
PURPOSE:To make the frequency characteristics of a diaphragm flat, by adhering a hard elastic body to a diaphragm made of a piezoelectric bimorph disc, adhering a solft elastic body and performing damping of the diaphrgam. CONSTITUTION:A piezoelectic element disc 12 is sticked to a metallic disc 11 to form a piezoelectric bimorph diaphragm and the assembly is supported in a ring shape with a comparatively hard elastic body 13 such as silicon rubber. Further, the elastic body 13 is supported with an elastic body 14 made of a softer substance such as sponge and foamed plastic than that of the elastic body 13 and closely adhered to a bottom plate 15. Oscillating parts 11-14 are covered with a frame 16 and a protecting plate 17 having small holes. Thus, even when a piezoelectric bimorph diaphragm is made small in size, an excellent damping characteristic can be provided, the frequency characteristics can be made flat and the diaphragm can simply be manufactured with an inexpensive material. |
