| 摘要 |
PURPOSE:To attain both miniaturization and low cost of a mechanical filter by providing at least two vertical oscillation mode converters containing the piezoelectric ceramics which is residually polarized in the thickness direction between two constantly elastic metallic plates of the same shape. CONSTITUTION:The vertical oscillation converters 12 and 12' are equal to each other, and constantly elastic metallic plates 13 and 13' of converters 12 and 12' are unified via connectors 16 and 16' respectively. The supporters 14 and 14' for mechanical filter are provided at the nodal points of the center part of the length direction at the opposite side to the connectors 16 and 16'. Then the piezoelectric ceramics polarized residually in the thickness direction with the same width and same length as metallic plates 16 and 16' are put on the plates 13 and 13'. Furthermore constantly elastic metallic plates 17 and 17' having same sizes as the plates 16 and 16' are adhered on the ceramics. At the same time, input/output terminals 15 and 15' are provided to the plates 17 and 17'. A mechanical filter of such a constitution shows the attenuation characteristics which are virtually free from spurious. |
