Performance of Tense Thin-Film Torsion Bar for Large Rotation and Low-Voltage Driving of Micromirror

In this paper, a micromirror device is developed by realizing the large rotation with the low-voltage driving. The maximum rotation angles observed at 5 V are 8.6deg with hysteresis and 7deg with little hysteresis at the static condition. The thin-film torsion bars contribute to decrease in the torsional spring constant. The tension is included for maintaining the compliance in the rotation of the mirror and for increasing stiffness in other movements. The performance of the torsion bar is investigated. The observed hard-spring effect is significant and this can be explained by the combination of the tension and the vertical displacement of the torsion bar