A biaxial PZT optical scanner for pico-projector applications

Abstract

We report a newly developed two-dimensional MEMS optical scanner based on the ADRIP (Arc Discharge Reactive Ion-Plating) deposited piezoelectric PZT film of typical 4 µm. A circular mirror of 1.2 mm in diameter is suspended within a pair of resonant mechanism that oscillates at 25 kHz for ±12° mechanical angle with a typical voltage of 10 V. A gimbal plate including the mirror is supported with another pair of meandering suspensions to tilt the plate in the orthogonal direction at 60 Hz for the off-resonant vertical motion of ±8° mechanical. Overall power consumption of the piezoelectric actuation was 100 mW or less. As a mechanical reinforce, a rib-structure was designed on the backside of the mirror by using a structural optimization tool TOSCA to suppress the dynamic curvature to 100 nm or less. A piezoelectric sensor was also integrated in the identical PZT film after optimizing the electrode shape to pick up the mechanical angle of the scanner and to give a trigger signal to the control system. A plug-in type pico-projector optics and electronics has been assembled in a 7.5 cm × 12 cm × 5 cm volume with RGB lasers to demonstrate a HD (high definition) class image projection of 720 horizontal lines. The fundamental resonance of the entire scanner mechanism was made to be 1 kHz or higher, thereby exhibiting a compatibility with vehicle applications.

Adaptive driving beam system with MEMS optical scanner for reconfigurable vehicle headlight

“…The shape of the backside support is determined using the structure optimization tool that takes the mechanical strength and the moment of inertia into the consideration of mirror's flatness and resonant frequency. 17…”

“…Typical resonant frequency was found at 21.3 kHz with a full-width-athalf-maximum of around 43 Hz, corresponding to a quality factor of 500. The scanner's oscillation angles were monitored by the built-in piezoelectric sensors reported elsewhere 17 to compose a feed-back control system.…”