| 摘要 |
<p>A micro-electromechanical system (MEMS) structure for an angular rate sensor, the structure comprising: first and second silicon-insulator composite wafers formed of silicon parts electrically isolated from each other by insulator material; a planar mono-crystalline silicon substrate structured to form a sensing system completely surrounded by a frame, the frame being positioned between the first and second composite wafers such that the sensing system is hermetically sealed between the first and second composite wafers, the sensing system including: two seismic masses having front and back surfaces; two driving beams, each having a first end attached to a seismic mass and a second end attached to the first and second composite wafers by means of fixed pedestals provided on the silicon substrate; and a bending spring arranged to directly connect the two seismic masses and synchronise their motion, the seismic masses and driving beams being arranged to have a first degree of rotational freedom about first and second axes that are substantially perpendicular to the plane of the silicon substrate, and a second degree of rotational freedom about a third axis substantially coincident with the longitudinal axis of the driving beams; means for generating and detecting a primary motion consisting of a primary oscillation of the two seismic masses, in opposing phases, in the first degree of rotational freedom; and means of detecting a secondary motion consisting of a secondary oscillation of the two seismic masses, in opposing phases, in the second degree of rotational freedom, wherein the sensing system is arranged such that, when the device is subjected to an angular velocity around a fourth axis that is substantially in the plane of the silicon substrate and perpendicular to the longitudinal axis of the beams, a Coriolis force arises which causes the secondary oscillation of the seismic masses.</p> |
