Patent ID: 6144118
Filing Date: 2000-11-07
Classification: H02K

Abstract:
A device positioning apparatus comprisinga stage configured to support the device,a platen supporting the stage,a plurality of drive motors co-planar with the stage and arranged around the stage that apply drive forces directly to the stage without any mechanical contact to the stage, the drive forces imparting planar motion to the stage in at least three degrees of freedom of motion,a plurality of fluid bearings operating between the stage and the platen, the fluid bearings constraining the planar stage motion in all remaining degrees of freedom,a controller connected to the drive motors and configured to control operation of the drive motors, andwherein each drive motor comprisesa top stationary coil,a bottom stationary coil, anda movable magnet adapted to move in a gap of predetermined length formed in-between the top and bottom stationary coils.