Fundamental research on tactile sensor system using the longitudinal mode quartz crystal resonator

作者研制的触觉传感器由一个纵模石英晶体谐振器组成，石英晶体长4.6mm，宽106 μ m，厚200 μ m，工作频率为600 kHz。其石英晶体已被用作时钟时间源。在作者移除石英谐振器的封壳之后，该封壳被固定在直径为1cm、高度为1cm的丙烯酸树脂圆柱形壳体的中心，并且石英谐振器比其高1mm，并且具有环氧树脂。本文从梅森等效电路出发，分析了粘弹介质中石英晶体纵模谐振器的特性。梅森等效电路有两个对应于石英表面的声学端口。一个表面是无应力的，另一个表面是粘弹性介质。H.L.Oestreicher已经分析了半无限粘弹性介质上振动球的声阻抗问题。作者假定石英谐振器的顶部形状为球形，并将此声阻抗应用于曼森等效电路。实验中所用的硅橡胶是各向同性不可压缩介质，其泊松比为0.49。因此，频率的理论方程包含了密度和剪切模量两个参数。当石英触觉传感器垂直附着在硅橡胶上，其重量为2g时，频率的偏移与粘弹性测试仪和橡胶测试仪的测量结果相关。频率的变化反映了它的硬度或柔软度。总之，证实了频率变化的理论方程与实验结果吻合得很好。

The author developed the tactile sensor consisting of a longitudinal mode quartz ctystal resonator, the length-extensional quartz crystal operated at 600 kHz, which was 4.6mm in length and 106 mum width and 200mum thickness. Its quartz crystal has been used as a clock time source. After the author removed a capsule of the quartz resonator, which was fixed in the center of an acrylic resin cylinder case 1cm in diameter and 1cm height in the condition of the quartz resonator being 1mm higher than it with epoxy resin. The author call it the quartz tactile sensor.The author analyzed the behavior of a longitudinal mode quartz crystal resonator attached to viscoelastic medium based on a Mason's equivalent circuit. The Mason's equivalent circuit has two acoustic ports which correspond to quartz surfaces. One surface is stress-free and another one is attached to viscoelastric medium. The problem of acoustic impedence of an oscillating sphere attached to semi-infinite viscoelastic medium was already analyzed by H.L.Oestreicher. The author assumed that the top shape of the quartz resonator was sphere and applied this acoustic impedance to a Manson's equivalent circuit. Finally the author obtained the theoretical equations of the frequency and the impedance change.Silicone rubber used in this experiment is isotropic and incompressible medium and Poisson's ratio of it is 0.49. Therefore the theoretical equation of frequency comprises both the density and the shear modulus of it as a parameter. When the quartz tactile sensor is attached vereically to sillicone rubber with its weight 2g, the shift in frequency correlate the measurements of both viscoelatic and rubber tester. The frequency change shows hardness or softness of it.In conclusion, it has been confirmed that the theoretical equation of frequency change is in good agreement with the experimental results.