A Piezoelectric Gyroscope With Self-Equilibrated Coriolis Force Based on Overtone Thickness-Shear Modes of a Lithium Niobate Plate With an Inversion Layer

We propose a new structure for piezoelectric gyroscope application. It is made from a Z-cut lithium niobate plate with a ferroelectric inversion layer. It is shown theoretically that when the plate is electrically driven into thickness-shear vibration in one of the two in-plane directions of the plate and is rotating about the plate normal, the Coriolis force due to rotation causes a thickness-shear vibration in a perpendicular direction with an electrical output, which can be used to measure the angular rate of the rotation. Different from existing thickness-shear mode piezoelectric gyroscopes, which are based on the fundamental thickness-shear modes, the proposed gyroscope operates with the second overtone thickness-shear modes because of the inversion layer for which the Coriolis force is a self-equilibrated system and does not transmit to the mounting structure. This implies higher quality factor and better performance.