| 摘要 |
PURPOSE:To reduce the basic resonance frequency, by making equal the diameter of a piezoelectric porcelain plate and metallic plate and holding a piezoelectric diaphragm plate with a frame via a soft rubber having conductivity. CONSTITUTION:The diameter of a piezoelectric porcelain plate 2 is made equal as that of a metallic plate 1, and a piezoelectric porcelain plate 2 is held to a frame 5 via conductive rubbers 9, 9'. Thus, since the condition close to the support at circumference can be realized through the presence of a conductive rubber, the basic resonance frequency can be lowered. |
