Basic Study of Threefold Rotatory Symmetric Form Quartz Vibrator for Triaxial Gyrosensor

Abstract

For the actualization of a monolithic triaxial gyrosensor, we have proposed a threefold rotatory symmetric form vibrator using a quartz crystal Z-cut wafer that can be etched to a complex shape. In the former proposed vibrator, however, an etching residue induces bilateral asymmetry in the detection arms. The asymmetry causes coupling between some vibration modes. Additionally, the former vibrator has a high driving input resistance that makes self oscillation difficult. Therefore, we design a modified vibrator to improve the structural symmetry and decrease the driving input resistance of the original vibrator. The modified vibrator has improved mirror symmetry as well as threefold symmetry, and adopts modified driving beams with through holes. The measurement results of the electrical characteristics of the trial vibrators show that the equivalent resistance of the driving mode of the improved vibrator has been reduced 49-fold compared with that of the conventional one. Consequently, we found that the novel vibrator has a highly symmetric form and a low driving resistance that facilitate self oscillation.