Patent ID: 7880864
Filing Date: 2011-02-01
Classification: G03B,G03F,H02K

Abstract:
1. A stage apparatus comprising: a first stage; a first actuator which drives said first stage in a first direction; a second stage mounted on said first stage; a second actuator which drives said second stage such that said second stage moves relative to said first stage; a first unit including a first movable magnet arranged at an end of said first stage in the first direction, and a first stationary magnet which faces said first movable magnet and generates a repulsive force against said first movable magnet when said first stage is positioned at one end of a stroke region in which said first stage moves in the first direction; and a second unit including a second movable magnet arranged at two ends of said second stage in the first direction, and a second stationary magnet which faces said second movable magnet and generates a repulsive force against said second movable magnet when said second stage is positioned at the one end of the stroke region in which said first stage moves in the first direction; wherein a ratio between the repulsive force generated by said first unit and the repulsive force generated by said second unit is equal to a ratio between a mass of said first stage and a mass of said second stage.