Development of a Vector Display System Based on a Surface-Micromachined Micromirror

This paper presents a small-size low-power portable vector display system. The display system uses a micromirror which consists of a simple two-thin-film structure and is fabricated using a surface-micromachining process, i.e., Polysilicon Multi User MEMS Processes. The micromirror exhibits rotational motion around two axes as well as translational motion through four repulsive-force electrostatic actuating units. The micromirror is free of the “pull-in” effect which is associated with conventional micro electrostatic actuators. The micromirror is operated in a nonresonant mode and is capable of static positioning. Measured data show that the micromirror can achieve an optical scanning angle of ±2.5° in each axis. The measured bandwidth (-3 dB) for each driving unit is 2000 Hz operating at a sinusoidal input voltage of 0-200 V. The settling times of the actuating unit are 2.75 and 3.32 ms with overshoots of 5% and 48% for step inputs of 200 to 0 V and 0 to 200 V, respectively. The portable vector display system is developed through integrating the micromirror, a laser source, the optics, and a microcontroller and is shown to be very effective in displaying complex geometries. Open-loop control methods using lookup table searching, spot dwelling, and scan speed control were developed to control the integrated portable device.