Nonlinear spring tuning by electrostatic combs in micro mirror scanner

Tuning of operation frequency of resonant-mode micro-mirror scanner is often needed for compensating fabrication errors. Moreover, the oscillation curve of the scanner often suffers a bend by a hard-spring effect of torsion bar. Combining an electrostatic comb spring with the torsion bar, the resonant frequency of the scanner is tuned and the hard spring nonlinearity is compensated. First, the theoretical approach is described. Next, from the experiments, it is shown that the proposed method is effective by applying DC and AC voltages to the electrostatic comb spring. The adjustments of the resonant frequency and the hard spring nonlinearity are useful for improving the operation characteristics of micro mirror scanner.