面向大行程垂直运动的电磁驱动式MEMS微反射镜

Electromagnetic driven MEMS micromirror for large piston stroke

本文提出了一种具有大行程垂直位移的电磁驱动式MEMS微反射镜。该MEMS微反射镜基于杠杆原理,以电磁力驱动杠杆的短臂扭转,从而使连接长臂的反射镜面产生较大的位移;采用对称设计的弹性铰链结构,抵消水平方向的位移,以保证反射镜面仅在垂直方向位移。其中,电磁力由固定于镜体结构的永磁体和置于镜体结构周围的电磁驱动组件共同产生。本文通过MEMS工艺加工实现了该MEMS微反射镜的镜体结构部分,并通过机械装配将电磁驱动组件与镜体结构相对固定。机械结构仿真表明:该MEMS微反射镜的杠杆机构的扭转角度与驱动扭矩成正比。电磁仿真表明:基于电磁力的驱动扭矩与线圈电流正相关。实验结果表明:初步设计的镜体结构和电磁驱动组件构成的MEMS微反射镜可以在±70mA的驱动电流情况下实现4mm的垂直位移,并表现出较好的重复性。由于线圈匝数、驱动电路和杠杆结构都有很大的优化潜力,因此该MEMS微反射镜的垂直位移在理论上还可以进一步提高。

This research suggests an electromagnetic drive type MEMS micromirror with a large piston stroke.Lever-based,the MEMS micromirror employs electromagnetic force to drive the short arm's twist,which causes the micromirror attached to the long arm to produce a significant displacement.To ensure that the micromirror movement only occurs in the vertical direction,the displacement in the horizontal direction is offset using an elastic silicon hinge with symmetrical design.Wherein the permanent magnet fixed to the micromirror structure and the electromagnetic driving component positioned around the micromirror structure work together to generate the electromagnetic force.In this research,the MEMS process was used to fabricate the MEMS micromirror structure,and mechanical assembly was used to relatively fix the electromagnetic driving component to the micromirror structure.Mechanical structure simulation shows that the torsion angle of the lever mechanism of the MEMS micromirror is proportional to the driving torque.Electromagnetic simulation shows that the driving torque based on electromagnetic force is positively correlated with the coil current.The experimental findings demonstrate that the MEMS micromirror has high precision and can achieve a vertical displacement of 4mm at a driving current of about±70mA.Considering there is so much space for improvement in terms of coil turns,driving circuit,and lever structure,the MEMS micromirror can theoretically accomplish more piston stroke.