Improved surface-micromachined hinges for fold-out structures

We describe a new surface-micromachined polysilicon micromechanical hinge that is designed for “foldout” surface-micromachined elements. The new hinge shows reduced wobble and enhanced accuracy as compared to previous foldout hinge designs. Features of the new hinge, which is built using only two structural layers of polycrystalline silicon, are two sets of cantilevers that are fixed to opposing hinge flanges. These cantilevers overlay an axle and thereby allow rotation while holding the rotating part to the support member. A precise locking mechanism for 90° out-of-plane rotation makes this hinge design especially suitable for applications to fixed-position vertical-foldout micromirrors. Measurements on such mirrors have confirmed predicted high precision in vertical locking. The new hinge has also permitted the construction of a mirror on a movable carriage that has been driven in a one-dimensional (1-D) sliding motion more than 100 μm by on-chip microvibromotors