| 摘要 |
PURPOSE:To prevent generation of noises by installing means to make the dynamic rigidity of a member uneven at the exact or approximate integral multiples of the half of each of the lengths lambda of a plurality of oscillatory waves which may generate noises of the different components of an oscillatory wave device. CONSTITUTION:The width of regions 2A1-2A7 and 2B1-2B7 forming A-phase and B-phase driving regions is made half as large as the length lambda of the bending vibration wave of an elastic body 1. If the elastic body has uneven dynamic rigidity, the natural frequency of the elastic body 1 corresponding to an oscillato ry wave in the tertiary mode with nodes at deep grooves 1B is high and that corresponding to an oscillatory wave in the tertiary mode with antinodes at the deep grooves 18 is the lower. The elastic body 1 has the different natural frequencies depending on the position of the oscillatory wave in the tertiary mode, therefore, an oscillatory wave in the tertiary mode which may generate noises does not act as a progressive wave. |
