Electrostatic 1D microscanner with vertical combs for HD resolution display

Abstract

An electrostatic 1 dimensionally (1D) scanning mirror for HD resolution display is introduced. Vertical comb drive was used to tilt the micro mirror. To minimize the moment of inertia and maximize the tilting angle of the mirror having the diameter of 1.6 mm, the rib was patterned on the backside of the mirror surface and optimized. Via the finite element simulation, the dynamic deformation of 45nm was achieved within the reflecting area in operating resonant mode thanks to the optimized rib structure. The actuating part of scanner was also optimized manipulating with several design variables to get maximum tilting angle. As the fabrication result, mechanical tilting angle of ±12.0 degree was achieved with the resonant frequency of 24.75kHz and the sinusoidal driving voltage of 280Vpp. For stable resonant motion of the scanner, the feedback control algorithm was realized in the driving circuit. Rigorous reliability characterization was carried out using statistical analysis on the fabricated samples. As a result, HD-resolution image with 720 progressive horizontal lines was demonstrated.

A review of fabrication processes for vertical comb drives

“…The custom thinned SOI process (Cho et al 2007) is similar to the full SOI wafer process, except that it begins by effectively fabricating its own SOI wafer. The handle wafer of the SOI wafer has trenches etched into the front of it before it is oxidized and bonded to the device layer.…”

MEMS Laser Scanners: A Review

“…The direct drive is easier to design and has a richer literature, but for each of the major actuation principles there are distinct advantages. ES scanners using a direct drive are performance limited by damping power losses and the small actuator capacitance due to limited available area when the fingers are to be directly connected to the mirror [43], [77]- [82]. Experimental evidence for significant reductions in air damping of ES when the comb finger gaps are increased Fig.…”

An electrostatically driven 2D micro-scanning mirror with capacitive sensing for projection display

“…Contrary to the DLP technology in which majority of the tasks for image production are realized optically, electronic design plays a more important role for scanning-type projectors. As demonstrated in prior studies, micro-scanning mirrors may be driven by electrostatic [5][6][7][8][9][10][11][12][13][14], electromagnetic [15][16][17][18] or piezoelectric [19][20][21][22][23] mechanisms. Each approach has its own advantages and disadvantages.…”