Shigematsu Takashi, Kurosawa Minoru Kuribayashi
Interdisciplinary Graduate School of Engineering, Tokyo Institute of Technology, Yokohama, Japan.
IEEE Trans Ultrason Ferroelectr Freq Control. 2008 Oct;55(10):2288-97. doi: 10.1109/TUFFC.927.
Design criteria for the stable and durable operation of a surface acoustic wave (SAW) motor are discussed. The low electric conductivity and pyroelectricity of the lithium niobate (LN) stator used in the motor hindered the motor's stability. We demonstrated that the use of LN whose conductivity had been enhanced by chemical reduction counteracted the instability caused by contact electrification and meniscus adhesion. The severe failure of the stator surface limits the durability of the SAW motor. Owing to the chemical inertness of LN, the surface failure of the stator was caused by mechanical stresses resulting from the indentation and sliding of the projections placed at the slider surface. The as-fabricated sharp edges of the projections are the obvious cause of failure. Thus, if the projections are necessary, a procedure in which the edges are worn off before operation is the only feasible method to correct this problem. Nevertheless, the optimum geometry to prevent surface failure was deduced as flat plane. The flat plane geometry was useful if the contact pressure is sufficiently large to diminish the effect of the layer of squeezed air between the surfaces.
讨论了表面声波（SAW）电机稳定持久运行的设计标准。电机中使用的铌酸锂（LN）定子的低电导率和热释电特性阻碍了电机的稳定性。我们证明，使用通过化学还原提高了电导率的LN可以抵消由接触起电和弯月面粘附引起的不稳定性。定子表面的严重失效限制了SAW电机的耐久性。由于LN的化学惰性，定子的表面失效是由放置在滑块表面的凸起的压痕和滑动产生的机械应力引起的。凸起的原始尖锐边缘是明显的失效原因。因此，如果需要这些凸起，在操作前将边缘磨损的程序是纠正此问题的唯一可行方法。然而，防止表面失效的最佳几何形状被推导为平面。如果接触压力足够大以减小表面之间挤压空气层的影响，则平面几何形状是有用的。
