A novel Si micromachined moving-coil induction actuated mm-sized resonant scanner

摘要

A novel silicon micromachined moving-coil scanner with electromagnetic induction actuation principle is presented. It was manufactured by the Si-LIG process, silicon-lithography-electroforming (Galvanoformung, from German), where its mechanical structure was made by bulk silicon micromachining of 200 gm thick (10 0) silicon substrate, and its armature was patterned by deep UV lithography and Au electroplating. The monolithic mechanical structure is a 12 x 24 mm(2) rectangular frame connected by 4.5 mm long torsion bars to a 4 x 10 mm(2) rectanaular rotor. On one face of the rotor is the armature, a 70 mu m thick, single turn, electroplated Au coil with 3.3 m Omega electrical resistance. The other face of the rotor was mirrored by a 1480 angstrom thick Al film. An external magnetic circuit generated a constant 0.115 T magnetic field parallel to the coil plane and a 0.01 T (peak value) field normal to the coil plane. A maximum mechanical deflection angle of 9.0 degrees pp at the 1311.5 Hz resonance frequency was measured, and a quality factor, Q, of 347 was achieved in air. A mathematical model for the device was derived and a dimensioning procedure was developed. The results show that electromagnetic induction actuation is adequate for mm-sized systems and capable of producing resonant scanners with performance compatible with applications such as bar code readers.