Surface acoustic wave gyroscope

设计了一种工作频率为15 MHz、波模为Rayleigh波、压电基片为128 Y-cut的声表面波陀螺。叉指换能器（IDT：称为“发生器IDT”）的电极和两个反射器对准以在表面上产生驻波。两个叉指换能器（称为“传感器叉指换能器”）和用于接收二次波的两个反射器垂直对准到产生一次驻波的电极中。扰动电极布置在IDT之间。这种陀螺仪的原理是接收由微扰电极随基片旋转而激发的二次波。利用等效电路模型估算了转速为2 π rad/s时的输出电压为几十mV。该传感器的电极为铝和铬，尺寸为25 mm × 45 mm，通过测量导纳特性曲线，发现传感器叉指换能器的反谐振频率与发生器叉指换能器的谐振频率不同，Q值较低。因此，输出电压将下降到小于100 μ V。并观察到波散射的扰动电极。这些散射波由传感器IDT检测。通过振动测试，发现了一些与我们设计的振动条件不同的微扰电极。此外，没有清楚地形成初级驻波。由于陀螺仪输出电压过低，采用振动台检测陀螺仪的输出。传感器IDT的输出被放大，并锁定在工作台振动的频率上。但是，不幸的是，还不能检测到输出电压。

A surface acoustic wave gyroscope using an operation frequency of 15 MHz, a wave mode of Rayleigh wave and a piezoelectric substrate of LiNbO3 128ﾟ Y-cut was designed. Electrodes of an interdigital transducer (IDT : called "generator IDT") and two reflectors are aligned for generating a standing wave on the surface. Two IDTs (called "sensor IDTs") and two reflectors for receiving a secondary wave are aligned perpendicularly into the electrodes which generate the primary standing wave. Perturbation electrodes are arranged between the IDTs. A principle of this gyroscope is receiving the secondary wave excited by the perturbation electrodes with rotation of the substrate. An output voltage of few tens of mV with rotation rate 2pi rad/s was estimated by using equivalent circuit models. This sensor with electrodes of aluminum and chromium and the size of 25mm x 45mm was fabricated by using photo-process.On sensor IDT,a different anti-resonance frequency from a resonance frequency of generator IDT and low Q factor was found from measuring admittance characteristic versus frequency. Therefor, output voltage will be decreased to less than one hundred muV.And waves scattered by the perturbation electrodes were observed. These scattered waves were detected by the sensor IDTs. Some perturbation electrode with different vibration condition from our design were found by vibration measuring. Further, the primary standing wave was not formed clearly. Thus, a vibrating table was used to detect the output of the gyroscope, for the output voltage was too low. The output of sensor IDT was amplified with locking in the frequency of table vibration. But, unfortunately, the output voltage could not detected yet.