US Patent 7242129 - Piezoelectric/electrostatic MEMS actuator

http://www.freepatentsonline.com/7242129.html

MEMS actuators have a variety of uses including read head drive controllers for optical disk drives or atomic force microscopes. As portable electronic devices continue to shrink MEMS becomes even more important in these types of memory drives. One problem however is the range of movement can be limited depending on the type of actuator used. This patent teaches using both piezoelectric and electrostatic combtooth actuation to enhance the range. Claim 1 reads:

1. A microelectromechanical system (MEMS) actuator comprising: a stationary comb fixed on a substrate; a movable comb disposed separately from the substrate; and a spring connected to the movable comb and the substrate to resiliently support the movable comb, wherein the movable comb includes a piezoelectric material layer in a laminated manner to be perpendicularly moved by a piezoelectric phenomenon and laterally moved by an electrostatic force to the stationary comb.