A new approach for improving the performance of MEMS vibratory gyroscopes was developed. The methodology suggests a simple way of improving the performance such as the overshoot, settling time and shock immunity by tuning the resonant frequency and the quality factor. The difference in the resonant frequency in two modes (driving and sensing mode) and the quality factors were found to be key factors in determining the dynamics of the gyroscopes. The difference in the frequency could be easily controlled by the electrical stiffness but it was difficult to control the quality factor because it is determined by vacuum level and the shape of structure. An electrostatic feedback technique allowed the control of the quality factor of the micro-gyroscopes. The experimental results show that the magnitude of the resonant peak in the frequency response of the gyroscope is reduced by 58% when the equivalent quality factor of the sensing system is tuned from 264 to 100 at a 100 Hz frequency difference between the driving and sensing modes. The time domain estimation was an approximate 50% reduction in the overshoot and an approximate threefold shortening of the settling time in that case. The estimation in the time domain was based on the simulation because there is no method to measure the transient response of gyroscopes directly.

This paper reports a novel high-sag microlens array (MLA) film with a full fill factor and presents its application to organic light emitting diodes (OLEDs) for the purpose of improving their outcoupling efficiency. A gapless hexagonal MLA film having a high sag ratio is proposed and fabricated by a simple micromachining process including trench formation and the conformal vapor phase deposition of a polymer. By applying the MLA films to OLED panels, the outcoupling efficiency was increased by a maximum of 48% without any apparent color shift. A high-sag MLA film with a full fill factor is expected to impart remarkable optical efficiency to various display or lighting applications with flat panel light sources including OLEDs.

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