An electrostatically driven torsional resonator with two degrees of freedom. (Part 1) - The principle and characteristics of motion

An electrostatically driven torsional resonator with two degrees of freedom (TDF) is proposed. The main characteristic of this resonator is that the electrostatic force is not applied to the moving element. The electrode gap does not lead directly to difficulties of consistency with low voltage driving and a large moving range. Displacement of the moving plate is ensured when the distance between the electrode plate and the fixed plate is minimized. The principle and a demonstration of he resonator with TDF are described. The resonator is fabricated from a silicon wafer using a micromachining technique. The mode of vibration is identified by the finite element method (FEM). The experimental results show that the displacement of the electrode plate is almost zero and that the moving plate vibrates at its antiresonance frequency. The characteristics measured in the experiment agree well with the value obtained by FEM modal analysis.