Slow scanning electromagnetic MEMS scanner for laser display

Abstract

A small size, low power consuming, shock proven optical scanner with capacitive comb type rotational sensor for the application of mobile projection display was designed, fabricated, and characterized. To get a 2-dimensional video image, the present device horizontally scans a vertical line image made through a line-type diffractive spatial optical modulator. In order to minimize device size as well as power consumption, the mirror surface was placed on the opposite side of the coil actuator. To prevent thermal deformation of the mirror, the mirror was partially connected to the center point of the coil actuator. For shock proof, mechanical stoppers were constructed in the device. The scanner was fabricated from two silicon wafers and one glass wafer using a bulk micromachining technology. The packaged scanner consists of the scanner chip, a pair of magnets, yoke rim, and base plate. The fabricated package size is 9.2mmx10mmx3mm (0.28cc) and the mirror size is 3mmx1.5mm. The scanner chip has no damage under the shock test with impact of 2,000G in 1ms. In case of full optical scan angle of 30°at 120Hz driving frequency, linearity and power consumption are measured 98% and 60mW, respectively, which are suitable for mobile display applications.