Air friction loss of comb drive resonant micro mirrors for laser scanning display

The electrostatically driven scanning micro mirrors are fabricated for the application to laser scanning display. However, a high voltage is needed for the operation. In order to operate mirror at a low voltage, we investigate the air friction loss of micro mirror with vertically driven comb in vacuum. Due to the operation in vacuum, the rotation angle increases by 52 times larger than that in atmospheric air at the same operation voltage, which corresponds to the decrease of operation voltage by a factor more than 7 at 24.5 kHz resonant frequency. The quality factor depending on air damping is investigated in pressure range from 10⁵ Pa to 10^-1 Pa. The theoretical analyses on air friction loss are also presented.