High performance microshutter display with space-division modulation

Abstract

A microshutter device is a kind of transmssive spatial light modulator; base on microelectromechanical system (MEMS) technology, it is used in flat panel display applications due to the improved performance from the simple structure and operation principle. In the thesis, a microshutter device with space-division modulation have been proposed and developed. The proposed microshutter device has multiple microshutters in a pixel and the grayscale level is controlled by the number of actuated microshutters. To actuate multiple microshutters, a novel voltage-controlled electrostatic actuation has been suggested. In the novel electrostatic actuation, applied analog voltage level controls the number of actuated microshutters by using the voltage distribution through a floating electrode and the hysteresis of the electrostatic actuation. The novel electrostatic actuation was verified theoretically by means of an equivalent electrical circuit model. The design of microshutter started from the specification of display. The display specifications were decided by the consideration of conventional portable devices like MP3 player and cellular phone. And next, the dimensions of microshutter, fabrication process, material of sacrificial layer and materials of microshutter were decided. The shape and the pull-voltage of microshutter were predicted from the developed analytical models and verified by comparison with FEM simulation results. The thickness ratio of titanium was decided to 20 % for the quarter circle shape and the pull-in voltage of the designed microshutter was predicted about 20 V. The curl shaped microshutters were fabricated by using stress-induced curling and the characteristics of microshutter, such as pull-in voltage, pull-out voltage, resonant frequency and switching time, were successfully measured. The measured pull-in voltage was almost the same with the predicted value from the model and simulation and very fast switching time was achieved from t...