Analysis and simulation of round gimbaled electrostatic torsion micro-mirror

This paper describes the static and dynamic characteristics of an electrostatically actuated round torsional micro-mirror with variable length electrodes based on the parallel-plate capacitor model. Normalized equations that govern the static actuation property of the round torsional micro-mirror device were derived. The relationship between rotation angle and driving voltage, and the dynamic equations were also introduced. An integral approximation was deduced to simplify the analytical simulation with error less than 2.5 %. The pull-in phenomenon was discussed leading to direct relationships of the electrode size with the pull-in angle and the maximum driving voltage taking into consideration the previous approximation. The modal analysis and mode shape has also been simulated. An excellent agreement between the static and dynamic finite element simulation and the mathematical analysis has been achieved.